Question

Answer the following questions based on the information provided below:

You are conducting a study to determine the impact of a new reading intervention on students test scores. You randomly assign 40 students to either the intervention group or the control group (those not participating in the intervention). You also break the students into morning and afternoon classes to determine which is the best time of day to conduct the intervention.

1. What is the dependant variable?

2. What is/are the independent variable(s)?

3. How many cells will there be?

4. If we divide the groups evenly how many students will appear in each cell?

5. What type of design is this? (Again, Be Specific!)

6. Assume that you conduct an ANOVA with 3 groups and 60 subjects (evenly divided between the 3 groups) and receive an F-value of 3.30. How would you write this result in a study? (Be sure to include whether or not it is a significant result)

Answer 1

1) The response variable or the dependent variable here recorded is the test scores.

2) We will study the effect of the new reading intervention and also determine the best time of the day.

Thus, the two effects/ independent variables here are reading group (intervention/control group) and time of the day (morning/afternoon)

3) Thus, there will be 4 cells as follows

	Morning	Afternoon
Intervention	(10 obs)	(10obs)
Control	(10 obs)	(10 obs)

4) By dividing equally we have 10 observations/cell

5) Here, since the subjects are assigned randomly in every cell and the effect of two factors is studied, this design is known as Randomised block design.

6)

We have, number of groups = k = 3

Total number of observations = N = 60

Therefore, numerator df = k - 1 = 2

Denominator df = N - k = 57

Critical F value = F_2,57,0.05 = 3.1588

Since, F = 3.30 > 3.1588, we can conclude that the averages of the 3 groups differ significantly