January 30 - Reliability & Validity

Important Characteristics of Measures

I. Validity vs. Reliability
1. Validity= appropriateness, correctness, meaningfulness, and usefulness of
inferences made about the instruments used in a study
2. Reliability= consistency of scores obtained, across individuals, administrators, and
sets of items

II. Relationship Between Reliability and Validity
Suppose I have a faulty measuring tape and I use it to
measure each student’s height. - My tool is invalid, but it’s still reliable.

On the other hand, if I have a correctly printed measuring tape... - My tool is both valid and reliable.
question 20 and 5
****If something is unreliable it is invalid, BUT it can be invalid and reliable*****

or valid and reliable

III. Types of Validity
a. Content Validity - do the contents of the measurement(ifnormation to be learned match the information on the test) match the contents of the validity
b. Criterion Validity - how well do two measures of something correlate with one another
1. –Predictive Validity
2. –Concurrent Validity (CRT measures what was learned that year;correlated or compared to grades for the year).
a. Convergent vs. Discriminant Validity (****test question: one way people give their content validity is to show it's correlation with some other measurement****) it's how we know that the SAT is a decent predictor of college success is b/c it has a decent correlation with college GPA

c. Construct Validity - constructing a test or constructing a mesureament by getting experts in the field who say yes, that really is being a part of the concept.
• Internal Validity - how well is your study designed, how well did you select your subjects, how well did you get into your subject (will discuss later)