Intro to Psych Assessment Flashcards
What does the MMPI Measure
Mental Health Needs - eg. psychological disorders
What is the Mean and SD of the MMPI
M = 50, SD = 10 (scores as a t-test)
What is the most popularly used IQ test?
Stanford Binet V
What is the Mean and SD of the Stanford Binet Inventory?
M = 100, SD = 15
What does the NEO-PIR measure
Personality variables (big 5)
How often are many psychological tests updated
Approx. every 10 years
Why are tests updated regularly
Because cultural and social values change and the tests need to be updated to reflect these
What is meant by Reliability?
Consistency of measurement of a test
What is Psychological Research?
Psych Research aims to make generalisations about a population from a sample of people.
What is Psychological Assessment?
A special kind of Psych research which seeks to make generalisations about specific individuals with a sample n=1
What is test-retest reliability?
When scores from the same test administered at different times are highly correlated at diff. time points (ie. r = close to 1)
What is the importance of a CI as it relates to test scores?
Because it provides a range of values between which you’d expect the test score to fall.
Why is consistency (reliability) important?
Because we want to know that our assessment of needs at one point is similar to our assessment of your needs at a future time . The test should not just refer to your needs in the moment, but generalise to your needs across time.
What is Psychological Testing?
The process of administering one or more psychological test.
What is validity?
Assesses the usefulness of inferences made from test scores.
How are testing and theory interconnected?
They are two aspects of the same thing, with good theory we can develop good tests and vice versa.
Psychometric theory is cumulative
There has been no serious rebuttal to psychometric theory.
Why is variance in psychological testing a good thing?
Because a test with good reliability that produces a wider spread of scores allows us to identify individuals more easily than a test with lower variability.
When is variance in psychological testing a bad thing?
When it is caused by error/noise (measurement error) rather than by actual individual differences.
What two types of variance exist in psychological testing?
- Individual variability (good)
2. Error/random variability aka measurement error (bad)
What is a good way of measuring Reliability.
The extent to which a test correlates with itself. High correlation = good reliability
Test-Retest reliability.
What are the two components of an observed score?
X (observed score) = T (true score) + E (error)
What are the assumptions of general model of reliability?
- Mean error of measurement = 0 (because it is random)
- True scores and errors are uncorrelated r the = 0
- Errors on different measurements are uncorrelated r e1e2 = 0
What are the formulas for test scores from classical test theory?
X=T+E
and
σ^2X = σ^2T + σ^2E (variance version)
What is the formula for the reliability coefficient?
r tt = σ^2T / σ^2X (= true score variance/observed score variance)
What statistical technique is commonly used to determine reliability?
Correlation
If r tt = 0.9, what percentage of variance in observed scores is attributed to the true scores?
= 90%
Note that this gives the same value as R squared would in a traditional correlation/regression. But test/retest reliability interprets this differently.
What values can r tt range between?
0 and 1 (0 = no reliability, 1 = perfect test/restest reliability)
How is measurement error determined using r tt?
1 - value of r tt = proportion of variance caused by measurement error.
What is the main aim of test developers?
Reducing measurement error!
What is the most common/simple way of measuring reliability?
The test-retest reliability
What is the reliability of gender questionnaires?
r tt = 0.95
Average reliability for individual items in a test
r tt = 0.25 (so having many items in a test important as a means of reducing measurement error).
What is used to quantify the CI around a persons test score?
The standard error of measurement.
Which describes the distribution of scores for an individual if they were to be tested an infinite number of times.
What is the formula for standard error of measurement?
σmeas = σx√(1-rtt)
What is the SEM (standard error of measurement) when r tt = 0
SEM = σx√(1-0) = σx
As reliability decreases, variability ________?
As reliability decreases, variability increases
What is the predicted true score?
A score that the CI is based around. It is corrected for the unreliability in the observed true score (so always closer to population mean) .
What happens to predicted true score when observed score is below the mean?
The predicted true score goes up (towards the population mean)
What happens to the predicted true score when observed score is above the mean?
The predicted true score goes down (towards the mean).
How does the reliability coefficient (r tt) relate to the predicted true score?
The predicted true score will move towards the mean by the value of the error term e.g. if rtt is 0.9, the PTS will move to/away from the mean by 0.1; if the rtt is 0.6, the PTS will move to/away from the mean by 0.4
How long is the interval between retesting for test-retest reliability?
No more than 6 months. Often over a few weeks or days.
What are the limitations of test-retest reliability testing?
Because re-testing may be influenced by practice effects, and tests that require problem solving will advantage performance on the re-test.
What kinds of tests are best suited to test-retest reliability?
Sensory Discrimination and Motor Tests that are not effected by repetition.
What is test-retest reliability?
When same test is given at two different time points and the correlation of the scores determined to see how reliable it is.
What is the reliability coefficient?
r tt (the correlation between test scores at two different time points)
What is Alternate-Form Reliability?
When the same person is tested at two time points using two different, but equivalent tests. Reliability coefficient is obtained by correlating score on first and second tests.