Question

The process of interference is assumed to be responsible for much of forgetting in human memory. New information going into memory interferes with the information that already is there. One demonstration of interference examines the process of forgetting while people are asleep versus while they are awake. Because there should be less interference during sleep, there also should be less forgetting. The following data are the results from an experiment examining four groups of subjects. All subjects were given a list of words to remember. Then half of the subjects went to sleep, and the others stayed awake. Within both the asleep and awake groups, half of the subjects were tested after 2 hours and the rest were tested after 8 hours. The dependent variable is the number of words correctly recalled. Using alpha = .05, test to see if either the main effects or the interaction is significant. If the interaction is significant, graph it and interpret it.

	Awake	Asleep
2 hours	22   27 18   25 24   19 21   26 19   23	26   39 31   25 29   28 35   32 33   31
8 hours	12   4 8    6 9    3 11   7 5   13	24   22 16   14 19   22 18   21 25   17

Answer 1

Levels of Factor 1 = 2  (Asleep and Awake)    
Levels of Factor 2 = 2  (testing after 2 hours and 8 hours)    
Replications per sample = 10      
       
The null and alternative hypotheses are       
Ho : Asleep or Awake is not a significant factor for process of forgetting      
Ha : Asleep or Awake is a significant factor for process of forgetting      
       
Ho : Interval of time for testing is not a significant factor for process of forgetting      
Ha : Interval of time for testing is a significant factor for process of forgetting      
       
Ho : There is no interaction effect between the two factors      
Ha : There is an interaction effect between the two factors      
       
Using Excel Data Analysis tool for ANOVA 2 factor with replication, we get the following ANOVA table      

Source of Variation	SS	df	MS	F	P-value	F crit
Factor 1 (Duration for test)	1651.225	1	1651.2250	126.8818	0.0000	4.1132
Factor 2 (Asleep or Awake)	1050.625	1	1050.6250	80.7311	0.0000	4.1132
Interaction	30.625	1	30.625	2.3533	0.1338	4.1132
Within	468.5	36	13.0139
Total	3200.975	39

α = 0.05 Level of significance     
      
p-value for Factor 1 = 0.0000      
0.0000 < 0.05 (Do not Reject Ho)     
Hence there is a main effect of Factor 1 (Testing after 2 hours and 8 hours duration)      
      
p-value for Factor 2 = 0.0000      
0.0000 < 0.05 (Do not Reject Ho)     
Hence there is a main effect of Factor 2 (Asleep or Awake)      
      
p-value for Interaction = 0.1338      
0.1338 > 0.05 (Reject Ho)     
There is no interaction effect between the two factors