2.1 psychometric measurement

2.1 psychometric measurement

Measurement

• an object of interest can be operationlized into a measure which will then generate an outcome (or observation)

in psychology we are usually interested in

• measuring complex & unobservable constructs → e.g., impulsiveness, social anxiety

in order to measure psychological constructs

• psychometric scale that assesses all possible aspects & behaviour of the construct

psychometric tool

• a standarized process used to measure a subjects mental attribute (e.g., trait, skill, ability) or behaviour, on the basis of a series of indicators (normally referred to as items)

A test provides a

• score

the score of a test allows us to

• infer the true level of the test-taker on the particular construct that the test is measuring

Latent vs. Observed

Psychometrical tool requirements

• a clear purpose → it has to evaluate the person on a particular construct

• a defined administration procedure that must be followed

• known psychometric properties: reliability (consistency of the measure) & validity (if it measures what it is meant to measure, & not other constructs)

Non-psychometrical tools

• thematic apperception test (Morgan & Murray)

Thematic apperception test (Morgan & Murray) → involves

• describing ambiguous scenes: subjects are asked to create a story explaining the scenes they are shown

Tests can be classified according to

• purpose of the test

• application method

• type of performance

• response format

• score interpretation

Diagnostic tests

• tests used in the context of psychological assessment to aid diagnosis & guide treatment

Example of Diagnostic tests

• MMPI-2 assess personality traits & psychopathology

Selection test

• tests used in recruitment processes to identify ideal candidates

Example of selection test

• the DiSC profile test evaluates four dimensions considered relevant to the workplace

Placement test

• tests that evaluate an individual in order to place her or him in a category appropriate to their abilities

example of Placement test

• a french level test to be assigned to the appropriate class when entering a language school

Achievement tests

• tests that evaluate the knowledge or skills a person has acquired during a given period of time

examples of Achievement tests

• final exams in any academic context

types of tests

• paper-&-pencil tests

• computer-based tests

computer-based tests

• computerized fixed testing

• computerized adaptive testing

computerized fixed testing

• a fixed set of items is administered to each respondent

computerized adaptive testing

• different items are presented depending on the answers to previous questions

• the test adapts to the respondent´s level

Speed tests

• they have a fixed time limit that must be strictly followed

• these tests usually include more questions than a person can answer in the given time, & questions are usually simple

speed tests are mostly used to measure

• abilities, skills, or knoweledge

Power tests

• test-takers are allowed to take as much time as needed to complete the test

• questions are usually more difficult than those of a speed test

• the time spent completing the test is not relevant for the evaluation

Typical performance test

• these tests do not have right or wrong answers

• they ask questions that different individuals will answer in different ways

• they aim to measure the typical behaviour of an individual

Maximum performance tests

• these tests have right & wrong answers

• they usually measure knowledge or skills

• e.g., school exam

Constructed response

• no options are provided

• the subject has to provide an answer

Examples of Constructed response

• open-ended essay (short or long)

• completion format

• drawing format

• performance-task format

Selected response tests

• options are provided

• the subject must generally choose one option

Examples of Selected response tests

• likert-scale

• continuous response format

• forced-choice format

open-ended essay

• open-ended questions where the subject is asked to write down his or her response

• might be a word limit

completion format

• respondents are asked to complete incomplete stimulus

Drawing format

• respondents are asked to either draw a figure or complete a figure

• usually assess cognitive abilities

Performance task format

• respondents are asked to perform a short, simple task

• what is considered correct/incorrect & how different outcomes are scored, has to be clearly defined in the technical manual

Likert-type scale

• usually between three to seven options are provided

• the respondent must check (or circle) just one

• the options are always ordered

Continuous response format

• respondents are asked to move a slider across a numerical continuum to rate a stimuli or statement

Forced-choice format

• respondents are presented with several options (generally from 2 to 4)

• they must choose the one that better represents them

response formats are instructed to

• choose the one test that applies the most to them

• used to avoid response biases & faking

Norm-referenced tests

• designed to rank test takers on a distribution of scores

• results are compared to those of their normative group

examples of Norm-referenced tests

• SAT exams

• IQ tests

Criterion-referenced tests

• designed to compare the results of the test-taker against a predetermined standard

example of Criterion-referenced tests

• Cambridge English certificate tests (B2, C1, C2)

Measurement consists in

• operationalizing an object into a measure in order to obtain outcomes (or observation)

Scores of most scales are

• interval-type data

  • the results can be ordered & differences between values are meaningful

psychometric tool has

• a clear objective

• comes with a defined administration procedure

• provides information about its psychometric properties

there are different ways to classify tests according to

• their purpose

• type of response format

• type of performance

• scoring