Let’s jump into reliability and validity this week.

Several Important Takeaways:

1. Reliability = Consistency, Validity = Accuracy
2. It is more important for an instrument or measure to be valid (accurate) than it is to be reliable (consistent)
3. Reliability can not be calculated, only estimated
4. There are two types of validity- internal and external.
5. Internal validity (does the test measure what it says it measures) is more important than external validity (generalizability of results)

Reliability and Validity Slide Deck

There are 9 threats to internal validity and 7 threats to external validity, notice the crossover between the two.