Blog

A researcher was interested in examining the effects of the daily amount of creatine (5 grams, 10 grams, 15 grams, 20 grams) on the 50-yard sprint time of 200 female runners who volunteered for the study. From these 200 participants, 50 participants were randomly assigned to a daily dose of 5 grams of creatine; 50 participants were randomly assigned to a daily dose of 10 grams of creatine; 50 participants were randomly assigned to a daily dose of 15 grams of creatine; and 50 participants were randomly assigned to a daily dose of 20 grams of creatine. After being on the creatine dosage for 2 weeks, each participant’s 50-yard sprint time was measured. If the 50-yard sprint time was measured using an electronic stopwatch and the reliability of the electronic stopwatch was .95, what would be your evaluation of the reliability of the stopwatch?

A researcher was interested in evaluating if there was a relationship between participants’ academic class rank in high school (e.g., 1st, 2nd, 3rd, etc.) and their class rank in College (e.g., 1st, 2nd, 3rd, etc.).  What statistic would you use?

A researcher developed an intervention designed to increase the strength of adults 85 years or older.  The researcher randomly selected 6 older adults, pretested the adults to determine their pre-intervention strength, implemented the strength training program for 10 weeks (1 training session/week), and then posttested them immediately following the last intervention session.  Higher scores represent greater strength. The null hypothesis for this study is:  

Is it appropriate to calculate a median for ordinal data?

5 older adults volunteered for a study interested in determining the strength of older adults. The 5 older adults were asked to do as many pull-ups as they could. The number of pull-ups for the 5 participants is listed below.  The pull-up results (X) were: 5, 2, 2, 7, 9 What is the median number of pullups?

A researcher developed the following regression equation to predict muscular strength (y) from fat mass (Fat) in undergraduate students.                                                                             predicted y = 1.0 + 0.7 (Fat)                                                                                           R2 = .49                                                                                    In this sample, what is the proportion of the variance in undergraduate students’  muscular strength that is explained by fat mass (Fat)?

When a researcher is evaluating the external validity of a research design, what is the researcher primarily focusing on?

If a researcher was planning a randomized controlled trial to evaluate the effect of an exercise intervention (intervention group vs. control group) on blood pressure, in which situation would you need a larger sample size to achieve the same level of power.  Assume all other factors are kept the same.

A researcher compared the average physical activity scores for males and females using an effect size (Cohen’s d) and found an effect size of -2.5.  What is your interpretation?

If you were conducting a pairwise comparisons of 2 means and the 95% confidence interval for the difference in the 2 means was from -14 to -2, what would you conclude?