Question

3. Neuroscience researchers examined the impact of environment on rat development. Rats were randomly assigned to be raised in one of the four following test conditions: Impoverished (wire mesh cage - housed alone), standard (cage with other rats), enriched (cage with other rats and toys), super enriched (cage with rats and toys changes on a periodic basis). After two months, the rats were tested on a variety of learning measures (including the number of trials to learn a maze to a three perfect trial criteria), and several neurological measure (overall cortical weight, degree of dendritic branching, etc.). The data for the maze task is below. Use the Microsoft Excel "Anova Single-Factor" Data Analysis tool to conduct a 1-way ANOVA test for the data in the following table:

Impoverished	Standard	Enriched	Super Enriched
22	17	12	8
19	21	14	7
15	15	11	10
24	12	9	9
18	19	15	12

1. What is your computed answer?
2. What would be the null hypothesis in this study?
3. What would be the alternate hypothesis?
4. What is your F_crit?
5. Are there any significant differences between the four testing conditions?
6. Interpret your answer in the context of the problem statement.

Answer 1

Go to Data --> Data Analysis --> Anova Single-Factor and ake the entries as follows:

Result:

Null hypothesis: The maze task population mean measure for all the four testing conditions are equal

Alternate hypothesis: At least one of the population mean measure is different for the other three conditions.

Fcrit = 3.2389

F = 12.7178 which is > Fcrit. So, the null hypothesis is rejected. So, there exist significant differences between the four testing conditions at a 5% significance level.

So, the study shows that the environment has a significant impact on the development of the rats.