Lesson 3 Flashcards
Validity
This is the ability of a test to measure what it purports to measure. Measure of accuracy
Types of Validity
- Content Validity- Established by showing that the test items are a sample of a universe in which the investigator is interested in.
- Construct Validity-This is when a test accurately measures a theoretical, non-observable construct or trait.(e.g IQ)
- Criterion Validity - If its useful for predicting a person’s behaviour in a specified situation(e.g. job performance) Can be predictive
Reliability
A test is considered reliable if it gives the test giver the same result repeatedly. Measure of precision
Types of Reliability
- Test-Retest Reliability- gauged by administering the test twice at two different points in time
- Inter-rater Reliability- gauged by having two or more independent judges score the test
- Parallel form Reliability- gauged by comparing two different tests that were created using the same content
- Internal consistency method- items that measure the same construct are compared to determine the test’s internal consistency.
Reliability vs Validity
If a test is reliable it does not mean it is automatically valid
Factors affecting Validity and Reliability
- Systemic Errors(Construction)
- Unsystematic Errors ( Administrative)
- Scoring Errors
- Environmental factors
- Response sets
Systemic Errors
- These are factors related to the construction of the tests. They are built into the test.
- If test questions are difficult, confusing or ambiguous they affect reliability negatively .
- People may read the same question and it means different things to different people
- Can be corrected through research and redesign of the test
Unsystematic Errors(Administrative)
- Factors that arise from random issues related to HOW the test is given or how its taken.
-These errors exist in either the instructions provided to the test-taker or those given to the psychologist who is conducting the test. - Instructions that interfere with accurately gathering information (e.g putting a time limit on tests that don’t require speed) reduce the reliability of the test.
Scoring Errors
-Errors in these instructions, such as making unsupported conclusions, reduce the reliability of the test
- Test construction begins with research to support the conclusions drawn but if the research has flaws, a systemic error may result
Environmental Factors
Such as uncomfortable room temperature or distracting sounds are one form of unsystematic errors that can affect results.
- Errors made by the psychologist providing a test are another type of environmental factor that can affect reliability. Human errors is always. a possibility
Response Sets
Validity can be affected by response sets which include:
1. Social desirability bias(saying what they think should be said )
2. Acquiescence (Agreeing or disagreeing with everything)
3. Deviation (Giving unusual or uncommon responses)
