A middle school wanted to evaluate the efficacy of a 6-month after-school program designed to teach 7th grade students math concepts. The program involved weekly sessions that used computer apps that had tutorials and practice problems. Students (n= 100) who were struggling in math (based on 6th grade math scores) were included in the program.  At the beginning of the year the students took a math pretest (reliability = .45) and scored a mean of 15 (out of 100). After 6-months 65 of the 100 students remained in the program.  These 65 students were posttested and scored an average of 45 on the identical test that was used at pretest (out of 100).  The reliability of the posttest was .75. For each threat to internal validity, define the threat and briefly discuss if this threat is likely. Statistical regression

A researcher was interested in comparing the effectiveness of 3 types of instructional materials for teaching 1 biology concept. The instructional materials included: using text materials, video materials, text + video materials.  25 10th grade Biology students were randomly assigned to each type of instructional material for a total of 75 students.  These 75 students were volunteers  recruited from an after-school program.  Students used the method for 1, 2-hour session and were then tested using a 20 item Biology exam. What specific statistical procedure (technique) would you use to test the null hypothesis for this study?

A researcher was interested in comparing the effectiveness of 3 types of instructional materials for teaching 1 biology concept. The instructional materials included: using text materials, video materials, text + video materials.  25 10th grade Biology students were randomly assigned to each type of instructional material for a total of 75 students.  These 75 students were volunteers  recruited from an after-school program.  Students used the method for 1, 2-hour session and were then tested using a 20 item Biology exam. What is the dependent variable(s)?

A researcher was interested in comparing the effectiveness of 3 types of instructional materials for teaching 1 biology concept. The instructional materials included: using text materials, video materials, text + video materials.  25 10th grade Biology students were randomly assigned to each type of instructional material for a total of 75 students.  These 75 students were volunteers  recruited from an after-school program.  Students used the method for 1, 2-hour session and were then tested using a 20 item Biology exam. The researcher used random assignment. List 1 other method the researcher could use to control and reduce extraneous and confounding variables?

If a researcher reported an effect size (Cohen’s d)  comparing the difference between males and females on mathematics of -1.50, what would be your interpretation of the size of the effect?

For  the following statement that might be found in a test manual, indicate what type of evidence of MEASUREMENT VALIDITY is indicated by the statement. A panel of experts reviewed the 50 items on the math test and judged the items to be clearly written and covered the instructional objectives.

What is the dependent variable? The prediction of depression in adulthood from the number of traumatic events experienced by first-generation college students. in childhood.  

A study investigated the number of hours 9th grade students studied for a science exam  and 9th grade students’ performance on the final exam in science for 9th grade students. What is the dependent variable in the above study?

The Columbian Exchange only had a significant impact on conditions in the New World (North America, Middle America, and South America).  Locations in Europe were not significantly impacted by the exchange of agricultural goods.

In which of the following places would you be least likely to encounter subsistence farming?