Question

1. conic memory is a type of memory that holds visual information for about half a second (0.5 seconds). To demonstrate this type of memory, participants were shown three rows of four letters for 50 milliseconds. They were then asked to recall as many letters as possible, with a 0-, 0.5-, or 1.0-second delay before responding. Researchers hypothesized that longer delays would result in poorer recall. The number of letters correctly recalled is given in the table.

Delay Before Recall
0	0.5	1
5	3	3
10	8	5
7	6	5
6	5	2
10	4	7
10	10	2

(a) Complete the F-table. (Round your values for MS and F to two decimal places.)

Source of Variation	SS	df	MS	F
Between groups	48	2	24	?
Within groups (error)	?	15	?
Total	?	17

(b) Compute Tukey's HSD post hoc test and interpret the results. (Assume alpha equal to 0.05. Round your answer to two decimal places.)

The critical value is    for each pairwise comparison.

c) Which of the comparisons had significant differences? (Select all that apply.)

a. Recall following no delay was significantly different from recall following a one second delay.

b. Recall following a half second delay was significantly different from recall following a one second delay.

c. The null hypothesis of no difference should be retained because none of the pairwise comparisons demonstrate a significant difference.

d. Recall following no delay was significantly different from recall following a half second delay.

2. An educator wants to evaluate four different methods aimed at reducing the time children spend "off task" in the classroom. To test these methods, she implements one method in each of four similar classrooms and records the time spent off task (in minutes) in each classroom. The results are given in the table.

Classroom Method
A	B	C	D
2	4	4	3
5	1	4	4
1	1	0	4
1	3	5	4
2	5	4	2
0	4	5	5
4	2	6	2
4	1	4	3
3	0	0	0

(a) Complete the F-table. (Round your answers to two decimal places.)

Source of Variation	SS	df	MS	F
Between groups	?	?	?	?
Within groups (error)	?	?	?
Total	?	?

3. After computing a one-way within-subjects analysis of variance at a 0.1 level of significance, a psychologist begins to calculate a Bonferroni procedure. If she will make a 5 pairwise comparisons, what will be the testwise alpha?

Answer 1

1(a)

Following is the output of one way analysis:

Anova: Single Factor
SUMMARY
Groups	Count	Sum	Average	Variance
Delay (0)	6	48	8	5.2
Before(0.5)	6	36	6	6.8
Recall(1)	6	24	4	4
ANOVA
Source of Variation	SS	df	MS	F	P-value	F crit
Between Groups	48	2	24	4.5	0.029451	3.68232
Within Groups	80	15	5.333333
Total	128	17

Following is the completed table:

Source of Variation	SS	df	MS	F
Between groups	48	2	24	4.50
Within groups (error)	80	15	5.33
Total	128	17

(b)

Using table, the critical value for , df=15 and k=3 is

From ANOVA we have MSE = 5.333

So Tukey's HSD will be

Following table shows the absolute difference between means:

	Difference
G1-G2	8-6=2
G1-G3	8-4=4
G2-G3	6-4=2

Since the difference for G1- G3 is not less than critical value 3.67 so this pair is significantly different.

Correct option:

Recall following no delay was significantly different from recall following a one second delay.