Question

1. A trainer is studying the effects of vitamin D on his athletes. He has realized that there are many potential confounding factors, such as gender and age. To limit the effect of these confounding variables, he decided to first group two athletes together based on these variables (for example, two 21-year-old males). Then he randomly assigned one person to receive the vitamin D and the other to receive a sugar pill.

What type of experimental design does this situation demonstrate?

• Matched-Pair Design

• Randomized Block Design

• Completely Randomized Design

• Simple Random Design

2. Jay wants to study nutrition and performance in schools using available data.

Which of the scenarios below will provide Jay with available data?

• Going to a local high school and asking the principal for information about students' previous grades, then interviewing a random selection of students about their eating habits.

• Going to a local high school and asking the principal for information about students' current and previous grades, then asking the health teacher for the results from a survey students took in health class.

• Going to a local high school and asking the principal for information about students' current and previous grades, then interviewing a random selection of students about their eating habits.

• Going to a local college and asking current undergraduates to report their grades and eating habits from high school.

3. Dave drives to work. While driving the car over nine days, he observes his daily average speed and lists it in the table below.

Day	Average Speed (MPH)
1	45
2	62
3	44
4	70
5	59
6	66
7	54
8	63
9	67

The median speed at which Dave drove to work was __________.

• 59 miles per hour

• 63 miles per hour

• 58.89 miles per hour

• 62 miles per hour

Answer 1

Question 1:

A matched - pair design is a special case of randamized block design. It can be used when the experiment has only two treatment conditions (here, Vitamin D and sugar pills) and subjects can be grouped into pairs based on sum blocking variable (here, age and gender). Then within each pair subjects are randomly assigned to different treatments.

Thus, here the correct answer is a matched-pair design.

Question 2:

Here, the correct answer is - Going to a local high school and asking the principal for information about students' current and previous grades, then asking the health teacher for the results from a survey students took in health class.

Since he wants to study nutrition and performance in schools so it is better to get the whole survey data of each and every students to get a better idea about comparison. Here, we get both previous and current year grades and the health results of every student. So correct answer is option 2.

Question 3:

Here, we have to calculate the median of speed at which Dave drove to work.

To do so we arrange the data in ascending order given by-

44,45,54,59,62,63,66,67,70

Now, here sample size n=9 which is odd,

median = (n+1/2) th observation

= 5th observation

= 62 miles per hour

So, the correct option is number four i.e, 62 miles per hour.