|A researcher compared the effectiveness of compressed versus distributed practice in preparing for a memory test. The independent variable for the study was the type of practice (compressed versus distributed practice), and the dependent variable was the performance on the memory test. Each of two groups memorized the definitions of 40 vocabulary words. In group A, there were 50 participants who were all under twenty-five years of age. Participants in group A used the method of distributed practice, studying for 30 minutes on each of four evenings. They were all tested together on the fifth morning at 7:00 A.M at a community college classroom. Due to the length of the study, over four evenings, only 30 participants were able to be tested on the 5th morning at 7:00 A.M. In group B, there were 50 participants who were all over sixty years of age. Participants in group B used the method of compressed practice, studying only from 6:30 P.M. to 8:30 P.M. on the evening before the test. They were tested the next morning at 7:00 A.M at their individual homes. All participants completed a recall test. The test measured how quickly participants recalled the definitions of the vocabulary words. The results showed that the mean difference between the distributed practice group and the compressed practice group was statistically different from each other.
Label and answer the following: 1. Identify at least one threat to internal validity 2. Identify at least one threat to external validity 3. Identify at least one characteristic that is both a threat to internal and external validity 4. What changes would you make to alleviate these threats? https://www.youtube.com/watch?v=V3StgmV1LsM