Historical and Cultural Perspective of Assessment PDF

Historical and Cultural Perspective of Assessment LORESSA JOY D. PAGUTA, MA, RPm LAIRA DEE A. BAROQUILLO, MA, RPm Department of Psychology Historical Perspective of Assessment Early Antecedents Evidence suggests that the Chinese had a relatively sophisticate...

Historical and Cultural Perspective of Assessment LORESSA JOY D. PAGUTA, MA, RPm LAIRA DEE A. BAROQUILLO, MA, RPm Department of Psychology Historical Perspective of Assessment Early Antecedents Evidence suggests that the Chinese had a relatively sophisticated civil service testing program more than 4000 years ago (DuBois, 1970, 1972). Every third year in China, oral examinations were given to help determine work evaluations and promotion decisions. 3 Early Antecedents Han Dynasty (206 B.C.E. to 220 C.E.) Test Batteries (two or more tests used in conjunction) were used Topics were civil law, military affairs, agriculture, revenue, and geography. Ming Dynasty (1368-1644 C.E.) National Multistage Testing Program involved local and regional testing centers equipped with special testing booths. Only those who passed this third set of tests were eligible for public office. Local Provincial National Public Office 4 Early Antecedents Reports by British missionaries and diplomats encouraged the English East India Company in 1832 to copy the Chinese system as a method of selecting employees for overseas duty. Because testing programs worked well for the company, the British government adopted a similar system of testing for its civil service in 1855. After the British endorsement of a civil service testing system, the French and German governments followed. In 1883, the US government established the American Civil Service Commission, which developed and administered competitive examinations for certain government jobs. 5 Charles Darwin and Individual Differences To develop a measuring device, we must understand what we want to measure. According to Darwin’s theory, some possess characteristics that are more adaptive or successful in a given environment than are those of other members. (The Origin of Species, 1859) Through this process, he argued, life has evolved to its currently complex and intelligent levels. 6 Charles Darwin and Individual Differences Sir Francis Galton, a relative of Darwin’s, soon began applying Darwin’s theories to the study of human beings. Hereditary Genius (1869) - some people possessed characteristics that made them more fit than others. Galton initiated a search for knowledge concerning human individual differences which is now one of the most important domains of scientific psychology. 7 Charles Darwin and Individual Differences Galton’s work was extended by the U.S. psychologist James McKeen Cattell, who coined the term mental test (Cattell, 1890). Cattell’s doctoral dissertation was based on Galton’s work on individual differences in reaction time. Cattell perpetuated and stimulated the forces that ultimately led to the development of modern tests. 8 Experimental Psychology and Psychophysical Measurement J. E. Herbart used mathematical models as the basis for educational theories that strongly influenced 19th-century educational practices. E. H. Weber followed and attempted to demonstrate the existence of a psychological threshold, the minimum stimulus necessary to activate a sensory system. G. T. Fechner devised the law that the strength of a sensation grows as the logarithm of the stimulus intensity. 9 Experimental Psychology and Psychophysical Measurement Wilhelm Wundt set up a laboratory at the University of Leipzig in 1879, and was credited E. B. Titchener succeeded the works of Wundt with founding the science of psychology and founded structuralism 10 Experimental Psychology and Psychophysical Measurement G. Whipple, a student of Titchener recruited L. L. Thurstone. Whipple provided the basis for immense changes in the field of testing by conducting a seminar at the Carnegie Institute in 1919 attended by Thurstone , E. Strong, and other early prominent U.S. psychologists. This seminar came up with the Carnegie Interest Inventory and later the Strong Vocational Interest Blank. 11 Experimental Psychology and Psychophysical Measurement Thus, psychological testing developed from at least two lines of inquiry: one based on the work of Darwin, Galton, and Cattell on the measurement of individual differences, and the other (more theoretically relevant and probably stronger) based on the work of the German psychophysicists Herbart, Weber, Fechner, and Wundt. Experimental psychology developed from the latter. From this work also came the idea that testing, like an experiment, requires rigorous experimental control. 12 Experimental Psychology and Psychophysical Measurement There are also tests that arose in response to important needs such as classifying and identifying the mentally and emotionally handicapped. Seguin Form Board Test (Seguin 1866/1907), was developed in an effort to educate and evaluate the mentally disabled. Kraepelin (1912) devised a series of examination for evaluating emotionally impaired people. 13 The Evolution of Intelligence and Standardized Achievement Test Binet-Simon Scale Standford-Binet Intelligence Scale First version of the test was published in (Terman, 1916) 1905. This instrument contained 30 items of L. M. Terman of Stanford University had increasing difficulty and was designed to revised the Binet test for use in the United identify intellectually subnormal individuals. States. Binet’s standardization sample consisted of Was the only American version of the Binet 50 children who had been given the test test that flourished. under standard conditions – that is, with The standardization sample was increased to precisely the same instructions and format. include 1,000 people, original items were The 1908 Binet-Simon Scale has been revised, and many new items were added. substantially improved and introduced the significant concept of a child’s mental age. 14 15 The Evolution of Intelligence and Standardized Achievement Test Army Alpha & Army Beta Robert Yerkes, who was then the president of the American Psychological Measured the Association was requested for assistance intelligence by the army. Required reading ability of illiterate Yerkes headed a committee of adults distinguished psychologists who soon developed two structured group tests of human abilities: the Army Alpha and the Army Alpha Army Beta Army Beta 16 The Evolution of Intelligence and Standardized Achievement Test Achievement Tests In contrast to essay tests, standardized achievement tests provide multiple- choice questions that are standardized on a large sample to produce norms In 1923, the development of standardized against which the results of new achievement tests culminated in the examinees can be compared. publication of the Stanford Achievement Test by T. L. Kelley, G. M. Ruch, and L. Standardized achievement tests caught on M. Terman. quickly because of the relative ease of administration and scoring and the lack of subjectivity or favoritism that can occur in essay or other written tests. 17 The Evolution of Intelligence and Standardized Achievement Test Wechsler Intelligence Scales Wechsler’s inclusion of a nonverbal scale A mere 2 years after the 1937 revision of thus helped overcome some of the the Stanford-Binet test, David Wechsler practical and theoretical weaknesses of the published the first version of the Wechsler Binet test. intelligence scales the Wechsler-Bellevue Intelligence Scale (W-B) (Wechsler, Among the various scores produced by the 1939). Wechsler test was the performance IQ. Wechsler-Bellevue scale contained several interesting innovations in intelligence Performance tests do not require a verbal testing. It yielded several scores, permitting response; one can use them to evaluate an analysis of an individual’s pattern or intelligence in people who have few verbal combination of abilities. or language skills. 18 19 The Evolution of Intelligence and Standardized Achievement Test Personality Tests (1920-1940) The earliest personality tests were Personality tests measured presumably structured paper-and-pencil group tests. stable characteristics or traits that theoretically underlie behavior. These tests provided multiple-choice and true-false questions that could be Traits are relatively enduring dispositions administered to a large group. (tendencies to act, think, or feel in a certain manner in any given circumstance) that The first structured personality test, the distinguish one individual from another. Woodworth Personal Data Sheet, was developed during World War I and was For example, we say that some people are published in final form just after the war optimistic and some pessimistic. (see Figure 1.6). 20 21 The Evolution of Intelligence and Standardized Achievement Test Personality Tests (1920-1940) Projective personality tests provide The first Rorschach doctoral dissertation ambiguous stimulus and unclear response written in a U.S. university was not requirements. completed until 1932, when Sam Beck, Levy’s student, decided to investigate the The Rorschach test was first published by properties of the Rorschach test Herman Rorschach of Switzerland in1921. scientifically. David Levy introduced the Rorschach in the Today, however, the Rorschach is under a United States. dark cloud. 22 23 The Evolution of Intelligence and Standardized Achievement Test Personality Tests (1920-1940) Thematic Apperception Test (TAT) by Henry Murray & Christina Morgan in 1935 TAT was more structured. The TAT required the subject to make up a story about the ambiguous scene. TAT purported to measure human needs and thus to ascertain individual differences in motivation. 24 The Emergence of New Approaches to Personality Testing Minnesota Multiphasic Personality Inventory (MMPI) Minnesota Multiphasic Personality Inventory (MMPI) published in 1943, began a new era for structured personality tests. MMPI authors argued that the meaning of a test response could be determined only by empirical research. MMPI, along with its updated companion the MMPI-2 (Butcher, 1989, 1990), is currently the most widely used and referenced personality test. 25 The Emergence of New Approaches to Personality Testing Factor Analysis Factor analysis is a method of finding the minimum number of dimensions (characteristics, attributes), called factors, to account for a large number of variables. In 1940s, J. R. Guilford made the first serious attempt to use factor analytic techniques in the development of a structured personality test. By the end of that decade, R.B. Cattell had introduced the Sixteen Personality Factor Questionnaire (16PF) – remains one of the most well-constructed structured personality tests and an important example of a test developed with the aid of factor analysis. 26 The Current Environment Beginning in the 1980s and through the present, several major branches of applied psychology emerged and flourished: neuropsychology, health psychology, forensic psychology, and child psychology. All areas of psychology depend on knowledge gained in research studies that rely on measurements. The meaning and dependability of these measurements are essential to psychological research. To study any area of human behavior effectively, one must understand the basic principles of measurement. A thorough knowledge of testing will allow you to base your decisions on facts and to ensure that tests are used for the most beneficial and constructive purposes. 27 Culture and Assessment Early Antecedents Culture may be defined as “the socially transmitted behavior patterns, beliefs, and products of work of a particular population, community, or group of people” (Cohen, 1994). Culture prescribes many behaviors and ways of thinking. Spoken language, attitudes toward elders, and techniques of child rearing are but a few critical manifestations of culture. Indeed, the influence of culture on an individual’s thoughts and behavior may be a great deal stronger than most of us would acknowledge. 29 Some Issues Regarding Culture and Assessment Non-Verbal Communication & Behavior When an assessment is conducted with the aid of a translator, different types of Facial expressions, finger and hand signs, problems may emerge: and shifts in one’s position in space may all - subtle nuances of meaning may be lost in convey messages. translation, or unintentional hints to the correct or more desirable response may be conveyed Of course, the messages conveyed by such - translated items may be either easier or more difficult than the original body language may be different from culture - some vocabulary words may change meaning or to culture. have dual meanings when translated. 30 Some Issues Regarding Culture and Assessment Standards of Evaluation Cultures differ from one another in the extent to which they are individualist or collectivist Collectivist culture (typically associated (Markus & Kitayama, 1991). with the dominant culture in many countries throughout Asia, Latin America Individualist culture (typically associated and Africa), value is placed on traits such with the dominant culture in countries such as as conformity, cooperation, the United States and Great Britain) is interdependence, and striving toward characterized by value being placed on traits group goals. such as self-reliance, autonomy, independence, uniqueness, and competitiveness. 31  Historical and Cultural Perspective of Assessment Cohen, R. J. & Swerdlik, M. E. (2018). Psychological Testing & Assessment, 9th edition. McGraw-Hill Education, New York Kaplan, R. M. & Saccuzzo, D. P. (2018). Psychological Testing : Principles, Applications, & Issues, 9th edition. Cengage Learning, Boston, MA  Legal and Ethical Considerations in Assessment LORESSA JOY D. PAGUTA, MA, RPm LAIRA DEE A. BAROQUILLO, MA, RPm Department of Psychology Definitions LAWS are rules that individuals must obey for the good of the society as a whole - or rules thought to be for the good of society as a whole. Some laws are and have been relatively uncontroversial while others are very controversial. Definitions ETHICS is a body of principles of right, proper, or good conduct. Code of professional ethics is recognized and accepted by members of a profession, it defines the standard of care expected of members of that profession. Definitions Standard of care is the level at which the average, reasonable, and prudent professional would provide diagnostic or therapeutic services under the same or similar conditions. However, members of the public and members of the profession have not always been on “the same side” with respect to issues of ethics and law. The Concerns of the Public The assessment enterprise has never been well understood by the public, and even today you might hear criticisms based on a misunderstanding of testing Possible consequences of public misunderstanding include fear, anger, legislation, litigation, and administrative regulations. The Concerns of the Public Concern about the use of psychological tests first became widespread in the aftermath of World War I, when various professionals (as well as nonprofessionals) sought to adapt group tests developed by the military for civilian use in schools and industry. The Concerns of the Public In 1969 an article, in Harvard Educational Review entitled “How Much Can We Boost IQ and Scholastic Achievement?” fires again the public concern about testing Its author, Arthur Jensen, argued that “genetic factors are strongly implicated in the average Negro–white intelligence difference” (1969, p. 82). What followed was an outpouring of public and professional attention to nature-versus- nurture issues in addition to widespread skepticism about what intelligence tests were really measuring. Legislation Table 2–1 (Cohen, p 57) presented several legislations enacted at the federal level that affects the assessment enterprise. In the 1970s numerous states enacted minimum competency testing programs: formal testing programs designed to be used in decisions regarding various aspects of students’ education. Legislation Truth-in-testing legislation was also passed at the state level beginning in the 1980s. The primary objective of these laws was to give test takers a way to learn the criteria by which they are being judged. Legislation Some truth-in-testing laws require providing descriptions of: (1) the test’s purpose and its subject matter, (2) the knowledge and skills the test purports to measure, (3) procedures for ensuring accuracy in scoring, (4) procedures for notifying test takers of errors in scoring, and (5) procedures for ensuring the test taker’s confidentiality. Legislation The EEOC has published sets of guidelines concerning standards to be met in constructing and using employment tests. In 1978 the EEOC, the Civil Service Commission, the Department of Labor, and the Justice Department jointly published the Uniform Guidelines on Employee Selection Litigation This is why law resulting from litigation (the court-mediated resolution of legal matters of a civil, criminal or administrative nature) can impact our daily lives. Litigation can result in bringing an important and timely matter to the attention of legislators, thus serving as a stimulus to the creation of new legislation Litigation has sometimes been referred to as “judge-made law” because it typically comes in the form of a ruling by a court. Concerns of the Profession In 1895 the American Psychological Association (APA) formed its first committee on mental measurement. Another APA committee on measurement was formed in 1906 to further study various testing-related issues and problems. In 1916 and again in 1921, symposia dealing with various issues surrounding the expanding uses of tests were sponsored. Concerns of the Profession 1954, APA published its Technical Recommendations for Psychological Tests and Diagnostic Tests, a document that set forth testing standards and technical recommendations. The following year, the National Educational Association (working in collaboration with National Council on Measurement) published its Technical Recommendations for Achievement Tests. Test User Qualification As early as 1950 an APA Committee on Ethical Standards for Psychology published a report called Ethical Standards for the Distribution of Psychological Tests and Diagnostic Aids. Test User Qualification Level A: Level B: Level C: Tests or aids that can Tests or aids that require Tests and aids adequately be some technical knowledge of that require administered, scored, test construction and use and and interpreted with substantial the aid of the manual of supporting psychological understanding and a general and educational fields such as of testing and orientation to the kind statistics, individual supporting of institution or differences, psychology of psychological organization in which adjustment, personnel fields together one is working (for psychology, and guidance with instance, (e.g. aptitude tests and supervised achievement or adjustment inventories proficiency tests). experience applicable to normal populations) Test User Qualification Code of Fair Testing Practices in Education this document presents standards for educational test developers in four areas: (1) developing/ selecting tests, (2) interpreting scores, (3) striving for fairness, and (4) informing test takers. Test User Qualification A psychologist licensing law designed to serve as a model for state legislatures has been available from APA since 1987. However, that law contains no definition of psychological testing. Testing People with Disabilities Challenges may include: (1) transforming the test into a form that can be taken by the test taker, (2) transforming the responses of the test taker so that they are scorable, and (3) meaningfully interpreting the test data. Computerized test administration, scoring, and interpretation For assessment professionals, some major issues with regard to CAPA are as follows. Access to test administration, scoring, and interpretation software. Comparability of pencil-and-paper and computerized versions of tests. The value of computerized test interpretations. Unprofessional, unregulated “psychological testing” online. Guidelines with respect to certain populations In general, the guidelines are designed to assist professionals in providing informed and developmentally appropriate services. Although standards must be followed by all psychologists, guidelines are more aspirational in nature. Example: Guidelines for Psychological Practice with Transgender and Gender Nonconforming (TGNC) People. The document lists and discusses 16 guidelines Legislation in the Philippine Context REPUBLIC ACT No. 10029 or an act known to be as Philippine Psychology Act of 2009 An act to regulate the practice of psychology and psychometrics in the Philippines to protect the public from inexperienced or untrained individuals offering psychological services Legislation in the Philippine Context "Psychometrician" means a natural person who holds a valid certificate of registration and a valid professional identification card as psychometrician issued by the Professional Regulatory Board of Psychology and the Professional Regulation Commission pursuant to this Act. Legislation in the Philippine Context As such, he/she shall be authorized to do any of the following: Provided, that such shall at all times be conducted under the supervision of a licensed professional psychologist: Legislation in the Philippine Context Legislation in the Philippine Context "Psychologist" means a natural person who holds a valid certificate of registration and a valid professional identification card as psychometrician issued by the Professional Regulatory Board of Psychology and the PRC for the purpose of delivering psychological services defined in this Act Legislation in the Philippine Context REPUBLIC ACT 9258 or the Guidance and Counseling Act of 2004 Crafted and designed to professionalize the practice of guidance and counseling in the Philippines Legislation in the Philippine Context Guidance Counselor: A natural person who has been registered and issued a valid Certificate of Registration and a valid Professional Identification Card by the PRB of Guidance and Counseling and PRC in accordance with RA 9258 and who by virtue of specialized training, perform for a fee, salary, or other forms of compensation the functions of guidance and counseling under Section 3 of RA 9258 Legislation in the Philippine Context PAP Code of Ethics Rights of Test Takers The right of informed consent Test takers have a right to know why they are being evaluated, how the test data will be used, and what (if any) information will be released to whom. With full knowledge of such information, test takers give their informed consent to be tested. The disclosure of the information needed for consent must, of course, be in language the test taker can understand. Rights of Test Takers The right to be informed of test findings Giving realistic information about test performance to examinees is not only ethically and legally mandated but may be useful from a therapeutic perspective as well. Test takers have a right to be informed, in language they can understand, of the nature of the findings with respect to a test they have taken. Rights of Test Takers The right to privacy and confidentiality The concept of the privacy right “recognizes the freedom of the individual to pick and choose for himself the time, circumstances, and particularly the extent to which he wishes to share or withhold from others his attitudes, beliefs, behavior, and opinions” (Shah, 1969, p. 57). Rights of Test Takers The right to privacy and confidentiality Confidentiality concerns matters of communication outside the courtroom, privilege protects clients from disclosure in judicial proceedings (Jagim et al., 1978, p. 459). Rights of Test Takers The right to the least stigmatizing label The Standards advise that the least stigmatizing labels should always be assigned when reporting test results.  Legal and Ethical Considerations in Assessment Cohen, R. J. & Swerdlik, M. E. (2018). Psychological Testing & Assessment, 9th edition. McGraw-Hill Education, New York Kaplan, R. M. & Saccuzzo, D. P. (2018). Psychological Testing : Principles, Applications, & Issues, 9th edition. Cengage Learning, Boston, MA A Statistics Refresher LORESSA JOY D. PAGUTA, MA, RPm LAIRA DEE A. BAROQUILLO, MA, RPm Department of Psychology Sampling and Sampling Techniques Sample vs Population A population is the set of all the individuals of interest in a particular study (Gravetter & Wallnau, 2017). A sample is a set of individuals selected from a population, usually intended to represent the population in a research study (Gravetter & Wallnau, 2017). Sampling is the process of selecting observations (a sample) to provide an adequate description and inferences of the population. 4/28/2023 3 4/28/2023 4 Sampling There are several reasons for researchers to do sampling rather than conducting a census. Four important reasons are as follows: 1. Low cost of sampling 2. Less time consuming in sampling 3. Scope of sampling is high 4. Accuracy of data is high 4/28/2023 5 Census vs Sample Survey Census Sample Survey Census collects information about every Survey collects information from a sample of member of the population. the population. Census takes a long time to complete. Surveys can be done in a shorter period of time compared to a census. Census is generally conducted by the Surveys can be conducted by anyone. government. Census are not conducted frequently. Surveys can be conducted more frequently. 4/28/2023 6 Probability vs nonprobability sampling Probability sampling is a method of selecting a sample wherein each element in the population has a known, nonzero chance of being included in the sample; otherwise, it is nonprobability sampling. Probability sampling techniques: Nonprobability sampling: Simple Random Sampling Convenience Stratified sampling Purposive Cluster sampling Quota Systematic sampling Snowball Multistage Sampling 4/28/2023 7 Simple Random Sampling Simple random sampling is a sampling method wherein all elements of the population have the same probability of inclusion in the selected sample. Strategies: Draw lots (lottery method) Random numbers 4/28/2023 8 Stratified Sampling Stratified sampling is a probability sampling method where we divide the population into nonoverlapping subpopulations or strata, and then randomly pick samples from each stratum. A stratum is a group whose members are of the same characteristics. 4/28/2023 9 4/28/2023 10 Cluster Sampling Cluster sampling is a probability sampling method wherein we divide the population into nonoverlapping groups or clusters, and then randomly select clusters. A cluster is a group whose members are not of the same characteristics. Clusters are also referred as natural groups. 4/28/2023 11 4/28/2023 12 Systematic Sampling Systematic sampling is a probability sampling method in which researchers select members of the population at a regular interval (or k) determined in advance. If the population order is random or random-like (e.g., alphabetical), then this method will give you a representative sample that can be used to draw conclusions about your population of interest. Example: You survey every 20th customer who leaves, every day for a week. 4/28/2023 13 Multistage Sampling In multistage sampling, you draw a sample from a population using smaller and smaller groups (units) at each stage. It’s often used to collect data from a large, geographically spread group of people in national surveys. Multistage cluster sampling: The Multistage random sampling: The researcher divides the population into researcher chooses the samples randomly groups at various stages for better data at each stage. Here, the researcher does collection, management, and interpretation. not create clusters, but he/she narrows These groups are called clusters. down the convenience sample by applying random sampling. 4/28/2023 14 Convenience Sampling Convenience sampling is a non-probability sampling method where units are selected for inclusion in the sample because they are the easiest for the researcher to access. This can be due to geographical proximity, availability at a given time, or willingness to participate in the research. 4/28/2023 15 Snowball Sampling Snowball sampling is a non-probability sampling method where new units are recruited by other units to form part of the sample. Snowball sampling can be a useful way to conduct research about people with specific traits who might otherwise be difficult to identify (e.g., people with a rare disease). 4/28/2023 16 Purposive Sampling This type of sampling, also known as judgement sampling, involves the researcher using their expertise to select a sample that is most useful to the purposes of the research. An effective purposive sample must have clear criteria and rationale for inclusion. 4/28/2023 17 Quota Sampling Sampling is done until a specific number of units (quotas) for various subpopulations have been selected. Quota sampling is a means for satisfying sample size objectives for the subpopulations. In probability sampling, the units are selected randomly while in quota sampling a non- random method is used—it is usually left up to the interviewer to decide who is sampled. 4/28/2023 18 A Statistics Refresher  Inferential statistics are methods used to make Descriptive inferences statistics are methods used from observations of a small to provide a concise group of people known as a description of a collection of sample to a larger group quantitative information. of individuals known as a population. 4/28/2023 20 Scales of Measurement and their Properties 4/28/2023 21 Frequency Distribution A frequency table is an ordered listing of number of individuals having each of the different values for a particular variable. A frequency distribution shows the pattern of frequencies over the various values. 4/28/2023 22 Three kinds of graphs are used to illustrate frequency distributions are the histogram (a), the bar graph (b), and the frequency polygon (c). 4/28/2023 23 Frequency Distribution 4/28/2023 24 Frequency Distribution 4/28/2023 25  skewed distribution - distribution in which the scores pile up on one side Skewness of the middle and are spread out on the other side; distribution that is not symmetrical. 4/28/2023 26 Frequency Distribution floor effect situation in which many scores pile up at the low end of a distribution (creating skewness to the right) because it is not possible to have any lower score. 4/28/2023 27 Frequency Distribution ceiling effect situation in which many scores pile up at the high end of a distribution (creating skewness to the left) because it is not possible to have a higher score. 4/28/2023 28 Kurtosis The term testing professionals use to refer to the steepness of a distribution in its center is kurtosis. 4/28/2023 29 Measures of Central Tendency The central tendency of a distribution refers to the middle of the group of scores. Measures of central tendency refers to the set of measures that reflect where on the scale the distribution is centered. Three measures of central tendency: mean, mode, and median. 4/28/2023 30 Measures of Central Tendency 4/28/2023 31 Measures of Central Tendency 4/28/2023 32 Measures of Variability (Dispersion) Variability is an indication of how scores in a distribution are scattered or dispersed. Statistics that describe the amount of variation in a distribution are referred to as measures of variability. Some measures of variability include the range, the standard deviation, and the variance. 4/28/2023 33 4/28/2023 34 Range The descriptive statistic that indicates the distance between the two most extreme scores in a distribution is called the range. Range = Highest score – Lowest score We usually use the range as our sole measure of variability only with nominal or ordinal data. 4/28/2023 35 Variance The variance is the average of each score’s squared difference from the mean. The more spread out the distribution has a larger variance because being spread out makes the deviation scores bigger. If the deviation scores are bigger, the squared deviation scores and the average of the squared deviation scores (the variance) are also bigger. 4/28/2023 36 Standard Deviation The most widely used number to describe the spread of a group of scores is the standard deviation. The standard deviation is simply the square root of the variance. The standard deviation indicates the “average deviation” from the mean, the consistency in the scores, and how far scores are spread out around the mean. 4/28/2023 37 Normal Curve Normal curve. specific, mathematically defined, bell-shaped frequency distribution that is symmetrical and unimodal; distributions observed in nature and in research commonly approximate it. 4/28/2023 38 Standard Scores A standard score is a raw score that has been Z Scores (zero plus or minus one scale) T Scores (fifty plus or minus ten scale) converted from one scale to Stanine another scale, where the A Scores latter scale has some IQ Scores arbitrarily set mean and Percentile Ranks standard deviation. 4/28/2023 39 4/28/2023 40 4/28/2023 41 Correlation Correlation is an expression of the degree and direction of correspondence between two things. The coefficient of correlation is the numerical index that expresses this relationship: It tells us the extent to which X and Y are “co-related.” 4/28/2023 42 Correlation If two variables simultaneously increase or simultaneously decrease, then those two variables are said to be positively (or directly) correlated. A negative (or inverse) correlation occurs when one variable increases while the other variable decreases. 4/28/2023 43 4/28/2023 44 A Statistics Refresher Cohen, R. J. & Swerdlik, M. E. (2018). Psychological Testing & Assessment, 9th edition. McGraw-Hill Education, New York Kaplan, R. M. & Saccuzzo, D. P. (2018). Psychological Testing : Principles, Applications, & Issues, 9th edition. Cengage Learning, Boston, MA