Readiness for school implies such a level of physical, mental and social development child, which is necessary for successful learning school curriculum and in which the requirements of systematic training will not be excessive, will not lead to disruption of the child’s health, disruption of socio-psychological adaptation and a decrease in the effectiveness of training.
Using various diagnostic techniques it must be remembered that age standards, associated with most methods, are not absolute and unchangeable, suitable for assessing the level of development at all times and for all children without exception. Norms are almost always relative and reflect the state of a particular sample of children from which these samples were obtained. In each specific case, when, as a result of the examination, a characteristic is given to the child, including an assessment of his level psychological development, indicates which sample or category of children the norm with which the development indicator is compared belongs to of this child. In addition, it should be taken into account that the norms themselves are changeable: as social development progresses, the average level of intellectual, personal and behavioral development of children changes. Consequently, it is impossible to use standards that were established more than ten years ago, since they require mandatory re-checking and correction every three to five years.
Study of readiness for schooling of older children preschool age produced using scientifically proven research methods, the quality of which is subject to strict requirements. Only valid, accurate and reliable methods should be used, otherwise serious danger receiving unreliable data and making errors in conclusions. The user of the method is responsible for the quality of the method used and for obtaining results that can be trusted.
There are a number of moral and ethical requirements for conducting diagnostic examinations of children. The main ones are the following:
results diagnostic examination under no circumstances should they be used to harm the child;
Diagnosis of children can and should be carried out (with the exception of special occasions from the field of medical or legal practice) only with the consent of the children themselves and their parents;
Parents, with the exception of those who have been deprived of parental rights by law, can know the results of a diagnostic examination of their children, as well as the conclusions that a specialist made based on them;
The results of a diagnostic examination without taking into account many other factors and without taking into account the opinions of teachers and parents cannot serve as a basis for determining the fate of the child and making a conclusion about the possibility of his education and upbringing;
Psychodiagnostics of children should be carried out in close cooperation of a psychologist, educator, and teacher.
To work with older preschoolers, diagnostic tools are used, which are tests that are divided into groups according to the following main characteristics: individual and group (collective), verbal and nonverbal, quantitative and qualitative, gradual and alternative, general and special.
Individual tests are designed to work with each subject individually; group tests allow simultaneous testing of several subjects. Verbal tests are based on the analysis of the subjects’ own statements; nonverbal tests use signs other than speech for generalizations and conclusions. Quantitative tests allow you to obtain numerical indicators of the degree of development of the property being studied, and qualitative tests provide its detailed descriptive characteristics. Gradual tests make it possible to express in numbers the degree of development of the property being studied using a certain scale; alternative ones allow only two mutually exclusive conclusions such as “yes” or “no”. General tests are designed to examine some psychological property of a general nature, for example general intelligence. Special tests evaluate some special property that distinguishes a person from other people, for example, verbal or figurative thinking.
In pedagogy, group tests dominate, since they are the most economical for a specialist. However, it should be remembered that data from group tests is never absolutely reliable, especially in the case of a low result. There are many reasons leading to an inadequate decrease in test indicators: an unfavorable neuropsychic state of the child at the time of the examination (confusion, excitement or anxiety associated with the examination, with being in a new environment or caused by previous random impressions; the child may be sick on that very day head, he may be upset about something, etc.); random distractions caused by the behavior of other children, etc. Consequently, based on the test results, final conclusions that negatively characterize the assessed level should not be drawn.
The practice of determining “readiness” and selecting children should not contain as diagnostic criteria only a set of indicators characterizing the stock of information, knowledge, operational skills, multiplied by the speed of reaction. In turn, methods should evaluate not only “learning” (“training”). The use of such techniques gives double negative effect: firstly, it targets parents and educators “at active training”, and secondly, for most children it creates a situation of inadequate demands. Methods of psychological and pedagogical diagnostics must be adequate to the specific objectives of the examination and aimed, first of all, at differentiating qualitative originality individual development, as well as the identification of “risk factors” in development, for a comprehensive assessment of the child’s development by comparing data from observations of parents and analysis of the child’s activity when performing a set of tasks.
Examinations can be carried out in the presence of parents. The only exceptions are those methods during which no, even accidental, influence on the child’s choice is allowed (for example, determining the dominance of a cognitive or play motive). In other cases, when completing tasks, the presence of parents is desirable. This gives children greater confidence, and, in addition, when parents personally see what tasks their children are performing, they do not have any doubts about the bias and inadequacy of the examination. If necessary, parents are given recommendations on what games, exercises, and activities can be done at home to prepare their child for school.
Children must be at least 5 years 6 months old at the time of examination. The procedure for determining readiness for school is carried out in the first half of the day from 9 to 12 o'clock, preferably on Tuesday or Wednesday, when the maximum level of children's performance during the week is observed. The total duration of children's work in one lesson is no more than 40-45 minutes. Tasks that children did not have time to complete during this time are transferred to the second lesson. If a child cannot cope with the general pace of work or refuses to perform it during a frontal examination, it is recommended to subject him to an individual check.
A prerequisite for a successful diagnostic examination is the transition of an adult from the position of a teacher to the position of a person conducting diagnostics. This inevitably entails a change in its activities. If in the process of everyday work the main goal is to teach, to achieve the correct answer in this moment, then in the process of diagnostics - to obtain reliable data on the state of the child’s readiness for school.
From the very beginning of the examination, it is important to analyze the child’s reaction to the examination situation: how open he is to contact, whether he is active (for example, studying the situation in the room, examining toys and objects in it with interest), or whether he is disinhibited (fussing, trying to get up, twirls something in his hands, etc.). It should also be noted the manifestation of lethargy, tension, reluctance to draw attention to oneself, and fear of entering into a conversation. All these facts can be associated both with the psychodynamic (innate) characteristics of the child, for example, impulsivity or rigidity, and with such qualities of his personality as anxiety or demonstrativeness. The observations obtained are subsequently compared with test data, which helps to understand the nature of intellectual or emotional abnormalities preschooler.
During the examination, one should alternate methods so that the study of memory follows the analysis of thinking, and the study of perception follows the study of creativity. It is recommended to start diagnostics with tasks that involve drawing (both on a free and on a given topic), giving the child time to enter into the examination situation. During the interview, it is necessary to establish friendly, relaxed contact with the child, create favorable conditions for him, a familiar, comfortable environment. All tasks must be carried out in game form and are perceived by children as games. A play situation allows children to relax and helps reduce stress. In a situation where a child is afraid to answer and does not communicate well with an adult, he should be emotionally supported; if necessary, use tactile contact: pat on the head, hug, accompanying the actions with a verbal expression of confidence that the baby will cope well with all the games. Such support and constant confirmation as the tasks progress that the child is doing everything correctly contributes to the establishment of contact between the experimenter and the subject, and ultimately guarantees the purity of the results. It should be noted that the tactic of approval, regardless of the actual result, is recommended in communication with all children, since a positive assessment from an adult is especially important to them.
During the examination, it is not recommended to rush children or rush with a hint; show your displeasure, dissatisfaction; emphasize negative results and analyze the results together with the parents in the presence of the child.
The examination results may be complicated due to:
· difficulties in contacting unfamiliar adults (sometimes this depends not on the child, but on his interlocutors);
· fear of bad results (parents are often very worried themselves and scare their children with the “exam”);
· inability of the subject (by various reasons) concentrate, concentrate attention;
· individual characteristics of activity (in particular, slow pace of work).
In the diagnostic process, not only the final result of the task is important, but also the progress of the work. Therefore, when a preschooler completes each task, it is necessary to note on the examination card the indicators of his activity, health status, difficulties, and necessary help.
If the diagnostic results show low level readiness for school and the child needs special correctional and developmental work, all sections reflecting his development at the time of the examination are filled out in the psychological map, the main problems of the child are recorded and a plan of appropriate measures is outlined. However, it should be remembered that it is unacceptable to make a diagnosis based on one or even several indicators. By themselves, in isolation, poor memory or high level imaginations indicate nothing. Bad memory may be compensated by good volition, and a very developed imagination may be present even with a diagnosis of schizophrenia. If, when checking psychological and pedagogical readiness for school, particularly serious deviations in the child’s activities are discovered, parents should be tactfully recommended to contact the appropriate specialists.
Diagnostics(from the Greek dagnostikos - able to recognize) is the process of recognizing a disease through targeted medical examination patient, interpretation of the results obtained and their generalization with diagnosis.
Diagnosis is nothing more than medical report about the presence of a certain disease in a given patient. Establishing a diagnosis is of cardinal importance in medicine, since it completely determines the type of subsequent treatment and recommendations for a given patient.
As section clinical medicine, diagnostics includes three main sections: semiotics, methods of examining the patient, methods of establishing a diagnosis.
- Semiotics– a clinical discipline that studies the signs (symptoms) of a disease and their significance in diagnosis. We distinguish several types of symptoms: specific - characteristic of diseases of a certain type (cough in diseases respiratory system), nonspecific – arising from diseases various types(fever, weight loss, etc.) and pathognomonic symptoms - occurring only with one specific disease (for example, diastolic murmur at the apex of the heart with stenosis mitral valve). Usually, various diseases manifests itself with many symptoms. A set of symptoms that have a common pathogenetic basis is called a syndrome (from the Greek syndrome - accumulation).
- Methods of diagnostic examination of the patient. Methods of diagnostic examination of a patient are divided into main groups: clinical - carried out directly by a doctor and additional (paraclinical), which are carried out as prescribed by a doctor using special diagnostic methods.
- Establishing a diagnosis is carried out on the basis of data from clinical and additional examinations of the patient, and implies a transition from an abstract assumption about the presence of a particular disease to a specific diagnosis (for a specific patient), which includes a set of anatomical, etiological, pathogenetic, symptomatic and social facts that take place in a specific case.
Clinical examination of the patient
The most historically early diagnostic methods include taking an anamnesis, general examination of the patient, palpation, percussion, and auscultation.
Anamnesis(from the Greek anamnesis - memory) - a set of information about the patient and the history of his illness, obtained through targeted questioning of the patient or people who know him. We distinguish two main directions in collecting anamnesis: anamnesis of the disease (anamnesis morbi) and anamnesis of the patient’s life (anamnesis vitae).
Anamnesis disease involves collecting data on the onset and nature of the disease. During the collection of anamnesis of the disease, the moment of occurrence of complaints and their changes over time are clarified, and possible reasons the occurrence of the disease, the methods of treatment undertaken (or self-medication) are clarified. A short history (from several hours to 1-2 weeks) indicates the presence of an acute pathological process, while a long history (weeks, months, years) indicates a chronic disease.
Life history involves collecting data about the mental, physical and social status of the patient. Components life history are: physical and mental development the patient in childhood and adolescence, current living and nutritional conditions, bad habits, place of work and length of service, past illnesses, injury or surgery, tendency to allergic reactions, heredity, as well as obstetric history in women. Anamnesis in children (up to a certain age) is collected by interviewing people caring for the child. When collecting anamnesis from patients with mental disorders, there is a need to distinguish a subjective history (the patient’s distorted view of his illness) from an objective history (the real state of affairs, ascertained from people who know the patient).
Examination of the patient- is important stage on a way successful diagnosis. We distinguish between general and special examination of the patient. General inspection carried out in all cases, regardless of the type of patient and his complaints. A special examination is carried out by specialists (gynecologist, ophthalmologist) using special instruments.
A general examination of the patient is carried out in a warm, isolated room with good lighting (preferably daylight).
The patient is examined according to a special plan. At the beginning they evaluate general state patient, body position, general form(habitus), posture, skin color, facial expression, height, body weight, gait. Then they examine the head, face, neck, torso, limbs, external genitalia, determine the condition of the subcutaneous adipose tissue, musculoskeletal system, and lymph nodes.
A competent and attentive examination of the patient can become the basis for a successful diagnosis or significantly narrow the range of suspected diseases.
Palpation(Latin рalpatio – stroking) – method clinical examination based on tactile (manual) examination of the patient. Using palpation, determine the location various organs(both in their normal localization and in the case of their displacement), the consistency and elasticity of body tissues, the nature of the movement of organs, local temperature, painful areas, location of the injury, the presence of pathological formations in various body cavities, etc. Palpation can be superficial or deep, and deep palpation is carried out only after superficial palpation. During a systemic study, sequential palpation of the skin, muscles and bones, chest, abdominal cavity, areas of accumulation of lymph nodes. For the best research internal organs apply special types palpations: bimanual palpation of the kidneys, transrectal palpation of the pelvic organs, vaginal palpation of the uterus and its appendages, etc.
Percussion(lat. percussion - tapping, blow) - a method of clinical examination of a patient based on tapping various parts body, followed by interpretation of the change in sound obtained by tapping. This method is mainly used to determine tissue compaction (dull sound), the presence of hidden cavities and airiness ( ringing sound), elasticity (drum sound). When different parts of the body are tapped, vibrations of the body tissues occur. These vibrations are perceived by the doctor's ear in the form of sounds. certain height. The pitch of the sound is proportional to the density of the area being tapped: percussion of the lungs (tissue with low density) produces low sounds, and when percussion of the heart ( thick fabrics) – high. The volume of the percussion sound is directly proportional to the strength of the percussion blow, and the denser the organ being percussed, the shorter the duration. Blunt percussion sound formed by percussion of zones with high density: muscles, bones, fluid accumulations in body cavities. Drum sound - characteristic of percussion of large cavities filled with air: the stomach cavity, pleural cavity with pneumothorax (accumulation of air in the pleural cavity).
Auscultation(Latin auscultare - listen, listen) - a clinical diagnostic method based on listening and interpreting the sounds produced during the work of internal organs. Auscultation can be direct (if the doctor places the ear to the surface of the patient’s body) and indirect (using various instruments that conduct and amplify sound - a stethoscope). Normally, the work of internal organs is accompanied by characteristic sounds. When internal organs are involved in a particular pathological process, the sounds accompanying their functioning change. Capturing and interpreting these sounds is the principle of percussion. So, for example, when various lesions wheezing occurs in the lungs and bronchi; when the heart valves are damaged, various noises arise, the nature of which can suggest a specific type of disease.
Taken together, the methods of clinical examination of the patient are an indispensable tool in the process of establishing a diagnosis. Mastery of the technique of clinical diagnosis of a patient and the ability to interpret the data obtained in this case allow the doctor to correctly guide the doctor on the path to establishing a diagnosis. The above research methods are publicly available and do not require any special tools, which makes them even more valuable in various situations when additional (hardware and laboratory examination methods) are unavailable.
Bibliography:
- Alekseev V.G. Diagnosis and treatment of internal diseases, M.: Medicine, 1996
- Bogomolov B.N. Differential diagnosis and treatment of internal diseases, M.: Medicine, 2003
- Tetenev F.F. Physical methods research in the clinic of internal diseases (clinical lectures), Tomsk: Tomsk University Publishing House, 1995
The site provides background information for informational purposes only. Diagnosis and treatment of diseases must be carried out under the supervision of a specialist. All drugs have contraindications. Consultation with a specialist is required!
Signs are externally observable and recorded symptoms.
The relationship between features and categories is ambiguous. One sign may have several categories behind it.
Signs are distinguished by the fact that they can be directly observed and recorded. Categories are hidden from direct observation. Therefore, in social sciences they are usually called “latent variables”. For quantitative categories, the name “diagnostic factors” is also often used. Diagnostic inference is a transition from observed features to the level of hidden categories. A particular difficulty in psychological diagnostics lies in the fact that there are no strict one-to-one relationships between features and categories. For example, one and the same external act of a child (tearing out a piece of paper from a diary) can be due to completely different psychological reasons (increased level of hidden factor“propensity to deceive” or an increased level of another hidden factor “fear of punishment”). For an unambiguous conclusion, one symptom (one action), as a rule, is not enough. It is necessary to analyze a complex of symptoms, that is, a series of actions in different situations.
Diagnostic conclusion - there is a transition from externally observable symptoms to the level of hidden categories.
Features of quantitative and qualitative approaches in psychodiagnostics: standardized and clinical methods.
Psychodiagnostic methods provide analysis of various symptoms and their systematic selection.
Psychodiagnostic methods are divided into qualitative and quantitative approaches.
Quantitative approach (standardized method):
Standardization (standard - standard) is the uniformity of the procedure for assessing the implementation of a methodology and conducting a test.
This includes all testing methods: questionnaires, intelligence tests, tests of special abilities and achievements.
Areas of application: easily measured psychological reality.
Peculiarities:
Economical (group, using computers).
Psychometrically or technically sound (correct diagnosis).
Qualitative approach (clinical method):
Individual case analysis. Not a pathology!
Understanding and expert assessment methods are used: conversation, observation, projective techniques, analysis life path, analysis of activity products.
Areas of application: difficult to measure psychological reality (meanings, experiences).
Peculiarities:
Strictly individual method.
Psychometrically not substantiated.
The effectiveness depends on the professionalism of the psychologist and his work experience.
5.Psychological diagnosis. Causes of diagnostic errors. Requirements for a psychological diagnosis.
Diagnosis- from Greek. Recognition.
Medical understanding of diagnosis:
Symptom - from Greek. A sign of some disease. They are divided into two types - subjective (interoceptive sensations) and objective (measurement results, blood test, ECG).
Syndrome - from Greek. Clutch. A natural combination of symptoms caused by a single pathogenesis (pathology), considered as an independent disease, or as a stage of a disease.
Diagnosis is the determination of the essence and characteristics of the disease based on a comprehensive examination of the patient.
The medical understanding of the diagnosis is firmly associated with the disease, a deviation from the norm. This understanding also prevailed in psychology, that is, a psychological diagnosis is always the identification of the hidden cause of the detected problem.
S. Rosenzweig proposed using diagnosis exclusively for “naming” any disorders or disorders.
Psychological diagnosis turns out to be broader than in medicine. Both in norm and in pathology. And normally, it is not necessary to search for any violations or disorders.
Psychological diagnosis(Burlachuk L.F.) - the result of the activities of a psychologist, aimed at clarifying the essence of individual mental characteristics of a person in order to assess them current state, forecasting further development and developing recommendations for psychotherapeutic and psychocorrective influences, determined by the task of a psychodiagnostic examination.
Subject of psychological diagnosis– there is an establishment of individual psychological differences in normality and pathology. The most important element is to clarify in each individual case why these manifestations are found in the behavior of the subject, what are their causes and consequences.
Requirements for a psychological diagnosis.
A psychological diagnosis has a detailed and complex (subjectivity, causality, presence of contradictions) nature.
Psychological diagnosis is the result of systemic technical diagnostics. Not only the individual units of analysis are described, but also their relationships. The reasons for such relationships are revealed and a behavioral forecast is made based on such analysis. The diagnosis cannot be made using one method.
A psychological diagnosis must be structured. Options mental state people must be brought into a certain system: they are grouped according to the level of significance, according to relatedness of origin, according to possible lines of causal origin. Specialists process the relationships of various parameters in a structured diagnosis in the form of diagnosticograms. The simplest option is a psychodiagnostic profile.
Causes diagnostic errors.
A. Levitsky sees the following as sources of inaccuracies and errors: insufficient time allotted for the examination, lack of reliable sources of information about the subject and the low level of our knowledge about the laws governing behavioral disorders.
A more complete analysis of the causes of diagnostic errors is presented by Z. Plevitskaya, who distinguished them into two main groups.
Errors related to data parsing:
observation errors(for example, “blindness” to traits important for diagnosis, personality manifestations; observation of traits in a qualitatively or quantitatively distorted form);
registration errors(for example, the emotional coloring of the entries in the protocol, which indicates more about the attitude of the psychologist towards the subject rather than about the characteristics of his behavior; cases when an abstract assessment is passed off as a substantive assessment, differences in the understanding of the same terms different people);
instrumental errors arise as a result of the inability to use equipment and other measuring equipment, both in the technical and interpretive aspects.
Errors related to data processing:
"first impression" effect- error based on overestimation of the diagnostic value of primary information;
attribution error- attributing to the subject traits that he does not have, or considering unstable traits as stable;
false cause error;
cognitive radicalism- a tendency to overestimate the value of working hypotheses and a reluctance to look for better solutions;
cognitive conservatism- extremely careful formulation of hypotheses.
A set of organizational, engineering and technical measures designed to determine the technical condition of gas pipelines, gas equipment (technical products) after the expiration of the design service life... Construction terminology
Diagnostic value of the examination Choice of diagnostic intervals. Diagnostic value of simultaneous examination based on a set of signs. We will call a simple sign the result of an examination that can be expressed by one of two symbols or a binary number, for example 1 and 0; Yes and no; And. In this regard, the result of a quantitative survey can be considered as a sign that takes on several possible states.
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Lecture 1 6
Subject. Diagnostic value of signs
Target. Give the concept of dand diagnostic value of signs.
Educational. Explain values of features at d diagnostics.
Developmental. Develop logical thinking and a natural - scientific worldview.
Educational . Cultivate interest in scientific achievements and discoveries in the telecommunications industry.
Interdisciplinary connections:
Supporting: computer science, mathematics, computer technology and MP, programming systems.
Provided: Internship
Methodological support and equipment:
Methodological development for the lesson.
Syllabus.
Training program
Working programm.
Safety briefing.
Technical teaching aids: personal computer.
Providing jobs:
Workbooks
Progress of the lecture.
Organizing time.
Analysis and checking of homework
Answer the questions:
What is entropy?
What requirements did Claude Chenon set for measuring information?
How are entropy and channel capacity related?
Bring m athematic properties of entropy.
What is the effectiveness of the original alphabet?
What is first order conditional entropy?
What is the purpose of mutual entropy orunion entropy?
What is the entropy of a complex system? ?
What is a content approach to change?
Give Hartley's formula and explain it.
Give Hartley's formula.
What is the alphabetic approach based on, what is the power of the alphabet?
What is Shannon information?
What is the amount of information, measure?
Define the information volume of a message, what are the different approaches?
What measures of information are identified within the framework of the structural approach tomeasuring information?
What determines the geometric measure of information?
What does combinatorialmeasure of information?
What does the additive measure of information measure determine?
What determines the amount of information in a message?
What is the volumetric transmission method based on?sequences of signs, signals?
What is in information theorycalled the amount of information?
What approaches to measuring information do you know?
What is the basic unit of measurement for information?
How many bytes does 1 KB of information contain?
Give a formula for calculating the amount of information while reducing the uncertainty of knowledge.
Lecture outline
- Simple and complex signs and their diagnostic weights
- Selecting the size of diagnostic intervals. Diagnostic value of simultaneous examination based on a set of signs.
- Required amount of information. Optimality conditions.
DIAGNOSTIC VALUE OF SIGNS
Introductory remarks.In technical diagnostics, the description of an object in a system of signs that have great diagnostic value is very important.. The use of uninformative features not only turns out to be useless, but also reduces the efficiency of the diagnostic process itself, creating interference in recognition.
Quantitative determination of the diagnostic value of signs and complexes of signs can be carried out on the basis of information theory.A sign is determined by the information that is entered by the sign into the state system.
Simple and complex signs and their diagnostic weights.
Simple and complex signs.Let there be a system Dn which is located in one of P possible states Di (i = 12, . . ., P). Let us now agree to call this system a “system of diagnoses,” and each of the conditions a diagnosis. In most cases, continuous various states of the system are represented by a set of standards (diagnoses), and the choice of the number of diagnoses is often determined by the objectives of the study. System State Recognition D is carried out by observing another system associated with it, the system of signs.
We will call simple signexamination result, which can be expressed as one of two characters or a binary number (for example, 1 and 0; “yes” and “no”; + and).
From the point of view of information theory, a simple sign can be considered as a system that has one of two possible states. If kj is a simple sign, then we will denote its two states: kj presence of a sign; kj absence of a sign. A simple sign can mean the presence or absence of a measured parameter in a certain interval, He may also be of a qualitative nature (for example, a positive or negative test result, etc.).
For diagnostic purposes, the range of possible values of the measured parameter is often divided into intervals and the presence of the parameter in a given interval is characteristic. In this regard, the result of a quantitative survey can be considered asa sign that takes on several possible states.
Let us agree to call a complex sign (category m) the result of an observation (examination) that can be expressed by one of m symbols. If, as usual, we choose numbers as symbols, then a complex sign (of digit m) can be expressed m - digit number (for example, a complex sign of the 8th digit is expressed as an octal number). A complex sign can also be associated with a qualitative examination if the assessment contains several gradations [for example, noise (increased, normal, weak) three-digit sign]. We will often call the digits of a sign diagnostic intervals.
Let's look at some signs.
Single digit sign (t= 1) has only one possible state. Such a sign does not carry any diagnostic information and should be excluded from consideration.
Two-digit sign (t= 2) has two possible states. Two-digit attribute states kj can be designated kj 1 and k j 2. Let, for example, a sign kj refers to the measurement of a parameter X, for which two diagnostic intervals are set: X< 10 и х >10. Then k j 1 corresponds to x ≤ 10, and kj 2 means x > 10.
These states are alternative since only one of them is implemented. Obviously, the two-digit attribute can be replaced by a simple attribute k j if we put k j 1 = kj and k j 2 = kj . This simple sign can be formulated as follows: reduced value parameter X.
Three-digit sign (t =3) has three possible meanings: kj l kj 2 k j 3 . Let, for example, for the parameter x Three diagnostic intervals are accepted:<5; 515; >15. Then for Gfiznak kj, characterizing this parameter, there are three possible values:
x≤5 5< x <15 x ≥15
t-bit sign k. has t possible states: k i
Diagnostic weights of features.
If the examination reveals that the sign kj has meaning for this object k jS then we will call this value the implementation of the attribute kj . Denoting it k * j, we will have k * j = k js.
As diagnostic weightimplementation of the feature kj for diagnosis Di we accept
(19.1)
where P(Di/kjS) probability of diagnosis Di provided that the sign kj got the value k js ; P (D i ) a priori probability of diagnosis.
Value Z D . (k JS ) calls c i magnitude oh value of information.
Table 9 Probability of overload occurrence,%
It follows from the table, for example, that 10% of serviceable engines have an overload of more than 2.5 g.
Based on statistical data, 80% of objects are in good condition (for the resource in question) and 20% are in faulty condition. The magnitude of the overload constitutes a sign kj having three intervals. For example, P (kj 3) = P (D 1) X P (kj 3 / D 1 + P (D 2) P (k j 3 / D 2) = 0.8*0.1 + 0.2*0.7 = 0.22.
The diagnostic weights of the attribute intervals will be as follows:
Note that the diagnostic weight of the second interval is zero. This is clear from physical considerations: from the condition that the vibration overload is in the range from 1.5 to 2.5 g , it is impossible to draw conclusions about the state of the object.
The diagnostic weight of the first interval for a faulty condition is equal to oo, which denies (according to statistical data) the possibility of a faulty condition.
Relationship between diagnostic weights of implementations of a simple feature.
Simple sign k f can have two implementations: kj 1 = kj , k j 2 = kj . In this regard, we can talk about the presence or absence of a sign kj . Diagnostic weight of the presence of a sign kj for diagnosis D t
(19.3)
Diagnostic weight of the absence of a sign
(19.4)
Since there are obvious relationships 
(19.5)
(19.6)
That
(19.7)
From formula (19.7) it follows that
always have different signs.
Note that if the sign k is incidental to this diagnosis, then both diagnostic weights are equal to zero.
Conditional and independent diagnostic weights.
Equalities (19.1) and (19.2) determine the independent diagnostic weight of a given feature implementation for diagnosis D. It is typical for a situation in which examination based on kf is carried out first or when the results of the examination for other characteristics are not yet known (for example, during simultaneous examination for several characteristics). It is also typical for the case when the probability of occurrence of a given implementation of a characteristic does not depend on the results of previous surveys.
However, it is known that the diagnostic value of the implementation of a feature in many cases depends on what implementations of the features were obtained in previous examinations. It happens that the symptom itself is not significant, but its appearance after some other one allows us to unambiguously make a diagnosis (establish the state of the system).
Let the examination be carried out first according to the sign k 1 and then according to k 2. When examining an object based on to g realization was received kls, and it is required to determine the diagnostic weight of the implementation k 2 p of feature k 2 for diagnosis D. In accordance with the definition of diagnostic weight
(19.8)
Formula (19.8) determinesconditional diagnosticweight of the attribute implementation.
Independent diagnostic weight this implementation
(19.9)
If signs k 1 b k 2 are independent for the entire set of objects with different diagnoses
and conditionally independent for objects with a diagnosis D t then the conditional and independent diagnostic weights of the implementation coincide.
Diagnostic weight of the implementation of a complex of signs.
Let us consider the diagnostic weight of implementations of a complex of features K , consisting of the sign k 1 with implementations k ls and feature K 2 with implementations k 2р . There are two options for conducting a survey based on a set of signs:consistent and parallel.
During a sequential (stage-by-stage) examination, first according to the sign K 1 and then by attribute K 2 we get that diagnostic weights match up.
The diagnostic weight of the implementation of a set of signs does not depend on the order of the examination.
Note that the concept of diagnostic weight of the implementation of a feature is applicable only in relation to a given diagnosis, as the degree of its confirmation or denial. Averaging the diagnostic weight over all implementations of the characteristic and over all diagnoses leads to the concept of the informative or diagnostic value of the examination.
Diagnostic value of the examination
Particular diagnostic value of the examination.The diagnostic weight of a particular implementation of a characteristic does not yet give an idea of the diagnostic value of the examination for this characteristic. For example, when examining a simple sign, it may turn out that its presence has no diagnostic weight, while its absence is extremely important for establishing a diagnosis.
Let us agree to consider the diagnostic value of examinations based on kj for diagnosis D t the amount of information contributed by all implementations of the attribute kj in establishing a diagnosis D. For m -bit sign
(20.1)
The diagnostic value of the examination takes into account all possible implementations of the characteristic and represents the mathematical expectation of the amount of information contributed by individual implementations. Since the value Z D (kj ) refers to only one diagnosis D then we will call it the private diagnostic value of the examination based on kj .
It should also be noted that Zd(kj) determines the independent diagnostic value of the examination. It is typical when the examination is carried out first or when the results of other examinations are unknown. Magnitude Z D . (kj) can be written in three equivalent forms:
If the sign kj is incidental to diagnosis D then examination on this basis has no diagnostic value(Z Di (k f )=0).
The greatest diagnostic value is carried out by examinations based on signs that are often found in a given diagnosis, but generally rare, and, conversely, on signs that are found rarely in a given diagnosis, but in general often. If there is a match P (kj / Dj) and P (kj) the examination has no diagnostic value. These findings are consistent with the intuitive rules used in practice, but now these rules are precisely quantified.
The diagnostic value of the examination is calculated in units of information (binary units or bits) and cannot be a negative value. The latter is understandable from logical considerations: the information obtained during the examination cannot “worse” the process of recognizing the actual state.
Selecting the size of diagnostic intervals.
Value Z Di (kj ) can be used not only to assess the effectiveness of the examination, but also to appropriately select the value of diagnostic intervals (number of digits). Obviously, to simplify the analysis, it is convenient to reduce the number of diagnostic intervals, but this may lead to a decrease in the diagnostic value of the examination.
With an increase in the number of diagnostic intervals, the diagnostic value of a sign increases or remains the same, but the analysis of the results becomes more labor-intensive. It should be borne in mind that an increase in the number of diagnostic intervals often requires the use of additional statistical material to obtain the necessary reliability of the interval probability values.
General diagnostic value of the examination.It is known that an examination that has little diagnostic value for one diagnosis may have significant value for another.
Diagnostic value of simultaneous examination based on a set of signs.
The diagnostic value of an examination based on a set of signs for the entire system of diagnoses is measured by the amount of information contributed by the systems to 1 and to 2 in system D:
(21.1)
where H(D) a priori entropy of the diagnosis system; N (D/k 1 k 2) expected entropy of the diagnosis system after examination based on characteristics k 1 and k 2 .
Building an optimal diagnostic process
Required amount of information.In diagnostic tasks, the selection of the most informative features to describe an object is extremely important. In many cases, this is due to the difficulty of obtaining the information itself (the number of sensors characterizing the working process of the machine is, of necessity, very limited). In other cases, the time and cost of diagnostic testing, etc., are important.
From a theoretical point of view, the diagnostic examination process can be represented as follows. There is a system that can be, with some probability, in one of the states that is unknown in advance. If the prior probabilities of states P (D ) can be obtained from statistical data, then the entropy of the system
(23.1)
As a result of a complete diagnostic examination based on a set of signs TO the state of the system becomes known (for example, it turns out that the system is in a state D 1 then P (D 1) = 1, P (Di) = 0 (i = 2, . . ., n ). After a full diagnostic examination, the entropy (uncertainty) of the system
H(D/K) = 0. (23.2)
The information included in the diagnostic examination, or the diagnostic value of the examination
J D (K) = Z D (K) = H (D) - H (D / K) = H (D). (23.3)
In reality, condition (23.2) cannot always be satisfied. In many cases, recognition is statistical in nature and it is necessary to know that the probability of one of the states is quite high [for example, P(D 1)=0.95]. For such situations, the “residual” entropy of the system N (D /K)≠ 0.
In practical cases, the necessary diagnostic value of the examination
(23.4)
where ξ survey completeness coefficient, 0< ξ < 1.
Coefficient ξ depends on the reliability of recognition and for real diagnostic processes should be close to unity. If the prior probabilities of the system states are unknown, then it is always possible to give an upper bound for the entropy of the system
, (23.5)
where p number of system states.
From condition (23.4) it follows thatthe amount of information that needs to be obtained during a diagnostic examination is given and it is necessary to build an optimal process for its accumulation.
Optimality conditions.When constructing a diagnostic process, one should take into account the difficulty of obtaining relevant information. Let us call the optimality coefficient of a diagnostic examination based on the criterion k f for diagnosis Di value
(23.6)
where Z D . (kj) diagnostic value of examination based on k 1 for diagnosis D . In general
Z Di(kj) determined taking into account the results of previous examinations;
c if coefficient of examination complexity by attribute k ) for diagnosis D , characterizing the complexity and cost of the survey, its reliability, duration and other factors. It is assumed that c if does not depend on previous examinations.
Optimality coefficient of examination for the entire system of diagnoses
(23.7)
The optimality coefficient will be greatest if the required diagnostic value is obtained with the smallest number of individual examinations. In general, the optimal diagnostic process should ensure that the highest value of the optimality coefficient of the entire examination is obtained (the condition for the optimality of the diagnostic examination).
Homework: § notes.
Fixing the material:
Questions for self-control
- What do they call simple sign?
- What is called difficult What is the sign?
- What does the use lead to?uninformative signs
- Explain how a simple sign is indicated.
- What is a complex sign?
- One-digit Two-digit Three-digit signs Define them.
- What is the diagnostic value of the examination, how is it calculated?
- What can be done to simplify the analysis on the interval?
- How is the diagnostic value of an examination based on a set of signs measured for the entire system of diagnoses?
- What is involved in choosing the most informative features to describe an object?
- Give a description of the optimality coefficient.
Literature:
Amrenov S. A. “Methods for monitoring and diagnostics of communication systems and networks” LECTURE NOTES -: Astana, Kazakh State Agrotechnical University, 2005.
I.G. Baklanov Testing and diagnostics of communication systems. - M.: Eco-Trends, 2001. Page 221-254
Birger I. A. Technical diagnostics. M.: “Mechanical Engineering”, 1978.240, p., ill.
ARIPOV M.N., DZHURAEV R.KH., DZHABBAROV S.YU.“TECHNICAL DIAGNOSTICS OF DIGITAL SYSTEMS” - Tashkent, TEIS, 2005
Platonov Yu. M., Utkin Yu. G.Diagnostics, repair and prevention of personal computers. -M.: Hotline - Telecom, 2003.-312 p.: ill.
M.E.Bushueva, V.V.BelyakovDiagnostics of complex technical systems Proceedings of the 1st meeting on the NATO project SfP-973799 Semiconductors. Nizhny Novgorod, 2001
Malyshenko Yu.V. TECHNICAL DIAGNOSTICS part I lecture notes
Platonov Yu. M., Utkin Yu. G.Diagnostics of computer freezes and malfunctions/Series “Technomir”. Rostov-on-Don: “Phoenix”, 2001. 320 p.
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