Question

EXPERIMENT ONE

On a standard test of attention span in children, Dr. Niederjohn wants to know whether attention span is different in children who play video games extensively.  He selects a sample of children who regularly play video games and those who do not and obtains the following attention-span data:

Video	No Video
23	19
19	17
28	24
21	21
24	27
27	21
28	23
23	18
25	19
23	22

1. Give the M and SD for each group:

	Video	No Video
M (Experiment 1)	24.1	21.1
SD (Experiment 1)	2.961	3.035

2. Using SPSS compute the appropriate test. Paste SPSS output here.

t-Test: Two-Sample
	Video	No Video
Mean	24.1	21.1
Variance	8.766667	9.211111
Observations	10	10
Hypothesized Mean Difference	0
df	18
t Stat	2.23745
P(T<=t) one-tail	0.019072
t Critical one-tail	1.734064
P(T<=t) two-tail	0.038144
t Critical two-tail	2.100922

EXPERIMENT TWO

Dr. Marek wants to replicate the previous study. She selects a different sample of children who regularly play video games and those who do not and obtains the following attention-span data:

Video	No Video
20	16
19	20
31	24
18	21
24	27
27	21
31	23
23	21
25	16
23	22

3. Give the Mand SDfor each group:

	Video	No Video
M (Experiment 2)	24.1	21.1
SD (Experiment 2)	4.56	3.35

4. The difference between the means in experiment 1 is the same asthe difference between the means in experiment 2.

5. The variability in experiment 1 is less thanthe variability in experiment 2.

6a. Given your answer to numbers 4 and 5, the results of EXPERIMENT TWOare less likely

to be significant compared to the results of EXPERIMENT ONE?  

6b. Why? How will the numerator and denominator of the t-obtained formula be affected by the answers to questions 4 and 5? Note: you will be graded in part on the clarity of your answer. When you make comparisons between the two experiments, clearly identify which experiment you are referring to.

7. Using SPSS compute the appropriate test. Paste SPSS output here.

With alpha set at .05, write a conclusion of the findings.

Be sure to report the appropriate statistic in APA style.   

EXPERIMENT THREE

Dr. Ziegler wants to replicate the previous study once again.  She selects a different sample of children who regularly play video games and those who do not and obtains the following attention-span data:

Video	No Video
25	21
21	19
30	26
23	23
26	29
29	23
30	25
25	20
27	21
25	24

8. Give the Mand SDfor each group.

	Video	No Video
M (Experiment 3)
SD (Experiment 3)

9. The difference between the means in experiment 1 is _________ the difference between the means in experiment 3.

less than

greater than

the same as

10. The variability in experiment 1 is _________ the variability in experiment 3.

less than

greater than

the same as

11a. Given your answer to numbers 9 and 10, the results of EXPERIMENT THREEare _________ to be significant compared to the results of EXPERIMENT ONE?  

a.less likely

b.more likely

c.equally likely

11b. Why? How will the numerator and denominator of the t-obtained formula be affected by the answers to questions 9 and 10? Note: you will be graded in part on the clarity of your answer. When you make comparisons between the two experiments, clearly identify which experiment you are referring to.

12. The difference between the means in experiment 2 is _________ the difference between the means in experiment 3.

less than

greater than

the same as

13. The variability in experiment 2 is _________ the variability in experiment 3.

less than

greater than

the same as

14a. Given your answer to numbers 12 and 13, the results of EXPERIMENT THREEare _________ to be significant compared to the results of EXPERIMENT TWO?  

a.less likely

b.more likely

c.equally likely

14b. Why? How will the numerator and denominator of the t-obtained formula be affected by the answers to questions 12 and 13? Note: you will be graded in part on the clarity of your answer. When you make comparisons between the two experiments, clearly identify which experiment you are referring to.

15. Using SPSS compute the appropriate test. Paste SPSS output here.

With alpha set at .05, write a conclusion of the findings.

Be sure to report the appropriate statistic in APA style.   

Answer 1

Experiment 3:

t-Test: Two-Sample Assuming Equal Variances
	Video	No Video
Mean	26.1	23.1
Variance	8.76666667	9.21111111
Observations	10	10
Pooled Variance	8.98888889
Hypothesized Mean Difference	0
df	18
t Stat	2.23744955
P(T<=t) one-tail	0.01907192
t Critical one-tail	1.73406361
P(T<=t) two-tail	0.03814383
t Critical two-tail	2.10092204

	Video	No Video
M (Experiment 2)	26.1	23.1
SD (Experiment 2)	2.96	3.03

The difference between the means in experiment 1 is ___the same______ the difference between the means in experiment 3.

The variability in experiment 1 is _the same as________ the variability in experiment 3.

Given your answer to numbers 9 and 10, the results of EXPERIMENT THREEare __more likely_______ to be significant compared to the results of EXPERIMENT ONE?  

Why? How will the numerator and denominator of the t-obtained formula be affected by the answers to questions 9 and 10? Note: you will be graded in part on the clarity of your answer. When you make comparisons between the two experiments, clearly identify which experiment you are referring to.

Numerator which is difference of means is equal in both the experiemnts. Denominator which is variablity is also same in both experiments. So the results are also more likely to be same