Chapter 5: Psychological Measurement

four steps to measurement process:

conceptually defining the construct, operationally defining the construct, implementing the measure, evaluating the measure

demand characteristics

cues to how the researcher expects participants to behave

operational definition

definition of a variable in terms of precisely how it is to be measured

conceptual definition of a psychological construct

describes the behaviors and internal processes that make up that construct, along with how it relates to other variables. It has a strong genetic component, remains fairly stable over time, and is positively correlated with the tendency to experience pain and other physical symptoms

content validity

extent to which a measure "covers" the construct of interest

face validity

extent to which a measurement method appears "on its face" to measure the construct of interest

interrater reliability

extent to which different observers are consistent in their judgements; have two more people observe the same thing you do

criterion validity

extent to which people's scores on a measure are correlated with other variables that one would expect them to be correlated with

discriminant validity

extent to which scores on measure are not correlated with measures of variables that are conceptually distinct

test-retest reliability

extent to which this is actually the case; across time; able to be redone

reactivity

how the participant reacts to the study

Cohen's K

interrater reliability is assessed using this analogous statistic when they are categorical

ratio level

involves assigning scores in such a way that there is a true zero point that represents the complete absence of the quantity; number of siblings, number of right answers on a test

interval level

involves assigning scores so that they represent the precise magnitude of the difference between individuals, but a score of zero does not actually represent the complete absence of the characteristic; IQ, temperature

ordinal level

involves assigning scores so that they represent the rank order of the individuals

precautions to minimize reactivity:

make procedure clear and and brief, guarantee participant's anonymity

constructs

not so straightforward or simple to measure; personality traits, emotional states, attitudes, and abilities

self-report measures

participants report their own thoughts, feelings, and actions

psychometrics

psychological measurement

Why can constructs be observed directly?

represent tendencies to think, feel, or act in a certain ways & they often involve internal processes

the big five

set of 5 broad dimensions that capture much of the variation in human personality

split-half correlation

splitting the items into two sets, then a score is computed for each set of items, the relationship between the two sets of scores is examined

three types of consistency:

test-retest, internal, interrater

measurement

the assignment of scores to individuals so that the scores represent some characteristics of the individuals

reliability

the consistency of a measure

internal consistency

the consistency of people's responses across the items on a multiple-item measure

validity

the extent to which the score from a measure represent the variable thy are intended to

test-retest correlation

the first time the test was done. vs. the second time; the correlation between the two

Cronbach's a

the most common measure of internal consistency used by researchers in psychology is a statistic

Steven's levels of measurement are important because:

they emphasize the generality of the concept of measurement & the levels of measurement can serve as a rough guide to the statistical procedures that can be used with the data and the conclusions that can be drawn from them

behavioral measures

those in which some other aspect of participants' behavior is observed and recorded

nominal level

used for categorical variables and involves assigning scores that are category labels; male or female (one or the other)

converging operations

when psychologists use multiple operational definitions of the same construct

social desirable responding

when the participant reacts to the study how you want them too