PSYC4022 Testing and Assessment Week Two Psychometrics Flashcards
Test
“An objective & standardized procedure for measuring a psychological construct using a sample of behavior” (Guion, 1998)
Raw Score
Unmodified account of test performance.
Standardisation
involves administering a test to a representative sample for the purpose of establishing norms.
Norms
Show the distribution of results for the sample from a certain population. Raw scores from the sample can be transformed to standard scores to enable the development of norms.
Normative Sample
Is the group of people whose performance on a particular test is analysed for reference in evaluating the performance of individual testtakers.
Criterion
is a standard on which a judgement or decision is based.
Criterion Referenced Evaluation
A method of evaluation and a way of deriving meaning from test scores by evaluating an individual’s score with reference to a set standard. For example, a certain level GPA to gain entry into Honours
Distribution
a set of test scores
Frequency Distribution
Where you tally the number of score occurances
Grouped Frequency Distribution
Where intervals are counted
Measures of Central Tendency
E.g. Mean, Medium, Mode
Measures of Variability/ Dispersion
Range, SD, Square Root of Variance
How good is a score of 46.5?
You’d need to know;
- What was the test? How did developers define the concepts
- What type of distribution/ test norm referenced or criterion referenced?
- Norms for test (if norm referenced) Cut off score if criterion referenced.
- Was it a raw score or a scaled score
- Mean for population; Standard deviation
- Reliability - not a chance happening
- How it is scored? What it is out of, what scale?
- Content and Construct Validity
- Qualifications/ Experience of the tester
- What population was sampled
The Normal Curve is also called the…
Gaussian Curve
6 Types of Distribution Curves are…
- Normal
- Bi-Modal
- Positively Skewed
- Negatively Skewed
- J-shaped
- Rectangular
What percentage of scores lie within 1, 2, 3, 4, 5 and 6 SDs of the mean?
- 34%
- 68%
- 82%
- 96%
- 98%
- 100%
A test is standardised when it has (3 Things);
- Supervised Administration
- Consistent conditions, instructions, wording and timing
- been administered to representative group from a target population (random, stratified or convenience)
Raw scores from the sample can be transformed into standard scores to enable the development of…
norms
The Ravens has a standard norm and a….
managerial norm
Which accounting firm developed the managerial norm for the Ravens?
Price Waterhouse Coopers
Standard Scores
Raw scores that have been converted from one scale to another, the latter scale having some arbitrary set mean and SD.
Z-score ** EXAM
(mean set at zero, and SD set at one), which results from the conversion of a raw score into a number indicating how many SD units the raw score is below or above the mean.
T-score ** EXAM
(mean set at 50 and SD set at 10 (50 plus or minus ten scale)). A scale that ranges from 5 standard deviations below the mean to 5 standard deviations above the mean. A raw score that falls at 5 SDs below the mean would be 0, and one that falls at the mean would be 50, and 5 above would be 100.
From Z Scores to T Scores Formula
= z (10) + 50