Thank you. I need step by step formulas and instructions on how to answer each s
ID: 3204443 • Letter: T
Question
Thank you. I need step by step formulas and instructions on how to answer each section to make sure I am doing this correctly.
1. Kate was bored one day and has always been very interested in psychology. She decided to conduct her own experiment by testing the effect of staring at people on how fast they drive away from a bus stop. Kate went to the corner of Ashland and Chicago and when the light turned red she would stare at the driver who was stopped behind the light and when the light turned green, she would use her stop-watch to measure how fast they drove away in seconds. Kate varied the length of time she stared at the driver: a short glance (a normal length), a full 10 seconds, the length of the entire light (20 seconds). She expected that the longer she stared at the driver, the faster they would drive away (i.e., the shorter the amount of time it would take them to leave the intersection).
(This really works – try it sometime!!)
Glance
10 Seconds
20 Seconds
7
6
4
5
4
6
6
5
3
4
3
4
7
5
3
6
5
5
4
5
6
3
6
4
7
4
3
7
3
3
What is the null hypothesis?
What is the research hypothesis?
Calculate the within-groups estimate for population variance. SHOW ALL FORMULAS AND WORK
What are the degrees of freedom for the numerator (between-groups) and the degrees of freedom for the denominator (within-groups)? What is the corresponding cut-off score on the F-Distribution table, using an alpha of .05?
Calculate the between-groups estimate for the population variance. SHOW ALL FORMULAS AND WORK
What is the F value? SHOW ALL FORMULAS AND WORK
Is there a significant difference between the groups? Explain in words your results.
Glance
10 Seconds
20 Seconds
7
6
4
5
4
6
6
5
3
4
3
4
7
5
3
6
5
5
4
5
6
3
6
4
7
4
3
7
3
3
Explanation / Answer
What is the null hypothesis?
There is no difference in the mean time across all 3 groups.
What is the research hypothesis?
The mean time is different atleast for 1 group
Calculate the within-groups estimate for population variance.
To measure the variation within groups, we find the sum of the squared deviation between scores on the exam and the group average, calculating separate measures for each group, then summing the group values. This is a sum referred to as the "within sum of squares" or WSS. In formula terms, this is expressed as:
WSS = (10)*Var(Glance) +10*Var(10 Seconds) + 10*Var(20 Seconds)
= 10(2.04+1.04+1.29) = 43.7
What are the degrees of freedom for the numerator (between-groups) and the degrees of freedom for the denominator (within-groups)? What is the corresponding cut-off score on the F-Distribution table, using an alpha of .05?
df(between groups) = 2
df(within groups) = 27
F crit = 3.354
What is the F value?
F = MS(Between groups)/MS(Within groups) = 5.83/1.61 = 3.604
Is there a significant difference between the groups? Explain in words your results.
Yes since F> Fcritical, the difference is significant at 5% level of significance.
Result:
The difference between the time the driver takes to drive away in the situation of glance, stare for 10 seconds and stare for 20 seconds is significant.
Excel ouptut :
Anova: Single Factor SUMMARY Groups Count Sum Average Variance Glance 10 56 5.6 2.266667 10_Seconds 10 46 4.6 1.155556 20_Seconds 10 41 4.1 1.433333 ANOVA Source of Variation SS df MS F P-value F crit Between Groups 11.66667 2 5.833333 3.604119 0.040987 3.354131 Within Groups 43.7 27 1.618519 Total 55.36667 29Related Questions
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