Week 1-2 Psychometrics

Question 1

Psychometric soundness

Answer 1

the reliability and validity of a test

Question 2

Reliability

Answer 2

Consistency of measurement, Precision with which the test measures and the extent to which error is present in the measurement

Question 3

Validity

Answer 3

The ability of a test to measure what it is intended to measure

Question 4

Cronbach’s definition of psychological test (3 criteria)

Answer 4

1. Test involves behavioural samples
2. The behavioural samples are collected in a systematic way
3. The purpose of the test is to compare the behaviour of two or more people

Question 5

Scaling

Answer 5

how numerical values are assigned to psychological attributes

Question 6

3 key properties of numbers

Answer 6

The property of identity
The property of order
Th property of quantity

Question 7

Norm-referenced tests

Answer 7

Norm referenced tests are used to compare a person’s test score with scores from a representative reference sample
e.g intelligence tests

Question 8

Criterion referenced tests

Answer 8

Criterion referenced tests are used to evaluate an

individual’s test score with reference to a set standard

Question 9

mastery tasks

Answer 9

Criterion referenced tests are typically used to gauge
achievement or mastery, so they are sometimes called
mastery tasks

Question 10

inter-individual differences

Answer 10

comparing the behaviour of different people

Question 11

intra-individual differences

Answer 11

comparing the behaviour of the same people at different times in different contexts

Question 12

4 factors that can negatively affect the

interpretation of test scores as valid

Answer 12

• demand characteristics
• social desirability effects
• malingering
• experimenter bias

Question 13

The property of identity

Answer 13

Represents “sameness” vs. “differentness” by sorting people into categories based on similarity of psychological features

Question 14

The property of identity: 3 rules

Answer 14

1 must satisfy the property of “identity”
2 the categories must be mutually exclusive
3 the categories must be exhaustive

Question 15

The property of order

Answer 15

• represents information about the relative amount of an attribute people possess
• When numerals have this property, they indicate the rank order of individuals on some psychological attribute

Question 16

The property of quantity

Answer 16

-conveys information about the magnitude of differences between individuals
-Real numbers can be used to represent the quantity of an attribute
-cases can be compared with each other in a
meaningful and informative way

Question 17

absolute zero

Answer 17

Absence of an attribute

Question 18

arbitrary zero

Answer 18

does not indicate the absence of an attribute

Question 19

Additivity

Answer 19

Unit size should remain constant—all units being counted should be equal

Question 20

Intelligence, aptitude, and personality test scores are ordinal in nature because

Answer 20

they indicate not the amount of intelligence, aptitude,

and personality traits, but rather the rank order of individuals

Question 21

In psychological measurement is additivty satisfied?

Answer 21

rarely, for example, in tests each question does not have equal difficulty

Question 22

Counting is a __________ but not _____________ condition for measurement

Answer 22

necessary, sufficient

Question 23

Is counting construed as measurement?

Answer 23

Simply counting various things is not necessarily construed as measurement.

The total sum needs to be construed to represent some sort of attribute (e.g., knowledge or competence)

Question 24

Steven’s (1946) four scales of measurement

Answer 24

Nominal
Ordinal
Interval
Ratio

Question 25

nominal

Answer 25

-categorising based on one or more attribute into mutually exclusive and exhaustive categories

Question 26

Ordinal

Answer 26

- allows classification - rank ordering is possible - does not indicate how greater one ranking is to another - numbers do not indicate units of measurement - no absolute zero point

Question 27

interval

Answer 27

- scales contain equal intervals between numbers - averaging possible - no absolute zero

Question 28

Ratio

Answer 28

- has absolute zero point | - all mathematical operations can be performed

Question 29

Psychologists prefer to think of their data as interval because

Answer 29

it gives them more flexibility to manipulate and analyse the data and use more powerful operations such as ANOVA which can only be used on interval or ratio data

Question 30

what levels of measurement can you compute the average for?

Answer 30

interval- or ratio-level but not if they are ordinal- or nominal-level

Question 31

Correlation coefficients are bounded within a range of

Answer 31

-1 and +1

Question 32

Two distributions can have the same _______ but very different dispersion of _______

Answer 32

Mean, Scores.

Question 33

Three meaningful ways to describe distributions

Answer 33

1 central tendency 2 variability 3 shape

Question 34

variability

Answer 34

The degree of variance in scores in a single distribution

Question 35

Various ways we can represent variability in a distribution of scores

Answer 35

range, interquartile and semi-interquartile ranges, average deviation

Question 36

variance and standard deviation reflect

Answer 36

variability, as the degree to which scores in a distribution deviate (differ) from the mean of the distribution.

Question 37

Variance

Answer 37

the mean of the squared deviations between scores on a distribution and their mean.

Question 38

Calculating variance

Answer 38

1. Subtract each score from the mean 2. Square every deviation 3. Sum the squared deviations and divide by the total number of scores in the distribution.

Question 39

The SD is equal to

Answer 39

To the squared root of the "average of the squared deviations about the mean", hence the SD is the square root of the variance.

Question 40

SD reflects variability in terms of the ____ ______________ _________, whereas variance reflects variability in terms of _______ _________ ______.

Answer 40

raw deviation scores, squared deviation scores.

Question 41

Covariability

Answer 41

The degree to which variability in scores in one distribution co vary with scores in another distribution

Question 42

simple frequency distribution

Answer 42

A table in which scores are listed according to the frequency they occur.

Question 43

Grouped frequency distribution

Answer 43

A table in which test scores are grouped into intervals/bins known as class intervals e.g 70-78

Question 44

Central tendency

Answer 44

Tells us about the typical response e.g median, mode or mean

Question 45

shape

Answer 45

e.g positively skewed or negatively skewed

Question 46

Approximately what percentage of scores occur between the mean and +1 standard deviation?

Answer 46

34%

Question 47

the variance of a composite variable is determined by:

Answer 47

1 the variance of each item within the composite | 2 the correlations among the items

Question 48

Approximately what percentage of scores occur between the mean and -1 standard deviation?

Answer 48

34%

Question 49

A standard score is a

Answer 49

raw score that has been converted from one scale to another scale

Question 50

Approximately what percentage of scores occur between ±1 standard deviations

Answer 50

68%

Question 51

The scale used for computing T scores ranges from __ standard deviations below the mean to __ standard deviations above the mean

Answer 51

5, 5

Question 52

Approximately what percentage of scores occur between ±2 standard deviations

Answer 52

95%

Question 53

The convariance only provides information about: a) the magnitude b) the direction

Answer 53

b) the direction

Question 54

Calculate percentile rank with access to the entire distribution of scores

Answer 54

An individual's percentile rank is the number of scores in the distribution that are lower than the individual's score divided by the total number of scores times 100

Question 55

The size of the covariance is influenced by the strength of the association between

Answer 55

the metrics of the two variables, such that between two variables that produce large scores ("large-scale" variables) will tend to be larger than a covariance that involves one or more variables that produce small scores ("small-scale" variables

Question 56

The correlation coefficient provides a clear representation of both

Answer 56

the direction and the magnitude of an association between two variables