EXPERIMENT ONE On a standard test of attention span in children, Dr. Niederjohn
ID: 3172529 • Letter: E
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)
SD (Experiment 1)
2. With alpha set at .05, write a conclusion of the findings.
Be sure to report the appropriate statistic in APA style.
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 M and SD for each group:
Video
No Video
M (Experiment 2)
SD (Experiment 2)
4. The difference between the means in experiment 1 is _________ the difference between the means in experiment 2.
less than
greater than
the same as
5. The variability in experiment 1 is _________ the variability in experiment 2.
less than
greater than
the same as
6a. Given your answer to numbers 4 and 5, the results of EXPERIMENT TWO are _________ to be significant compared to the results of EXPERIMENT ONE?
a.less likely
b.more likely
c.equally likely
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. 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 M and SD for 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 THREE are _________ 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 THREE are _________ 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. With alpha set at .05, write a conclusion of the findings.
Be sure to report the appropriate statistic in APA style.
Video
No Video
23
19
19
17
28
24
21
21
24
27
27
21
28
23
23
18
25
19
23
22
Explanation / Answer
1.
Mean, Xbar=sigma X/N, where, X denotes attention span scores for children, N is sample size.
Video, X1bar=(23+19+...+23)/10=241/10=24.1, No Video,X2bar=211/10=21.1
Standard deviation, s=sqrt[1/n-1 sigma (X-Xbar)^2]
Video, s1=sqrt[1/10-1 {(23-24.1)^2+(19-24.1)^2+...+(23-24.1)^2}]=2.961
No Video, s2=sqrt[1/10-1 {(19-21.1)^2+(17-21.1)^2+...+(22-21.1)^2}]=3.035
2. H0: mu1-mu2=0 (there is no difference in population mean attention span scores for children watching videos and children not watching videos)
H1:mu1-mu2=/=0 (there is difference in population mean attention span scores for children watching videos and children not watching videos)
Assume independent group assumption, independence assumption, randomization condition and nearly normal conditions are reasonably met.
Use 2-sample t test.
t=(x1bar-x2bar)/sqrt[s1^2/n1+s2^2/n2]
=(24.1-21.1)/sqrt[2.961^2/10+3.035^2/10]
=2.24
p value at 17 df is 0.039.
df=[{(s1^2/n1+s2^2/n2)}^2/{1/n1-1(s1^2/n1)^2+1/n2-1(s2^/n2)^2}]
Reject H0, if p value is less than 0.05. Here, p value is not less than 0.05, therefore, fail to reject H0, there is not sufficient sample evidence to conclude that there is significant difference in population mean attention span scores for children watching videos and children not watching videos.
There was not a significant difference in the attention scores for children watching videos (M=24.10, SD=2.96) and and children not watching videos (M=21.10, SD=3.03) conditions, t(17)=2.24, p>0.05.
3. Applying the formula for mean and standard deviation (stated in ans 1) the results are as follows:
4. The difference in mean for experiment 1 is (24.1-21.1) is 3 and same as difference in mean for experiment 2 is (24.1-21.1) is also 3.
Video No Video Mean 24 21.1 SD 2.961 3.035Related Questions
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