Observational Study

Chi square and T-Test Assignment
Complete each step so I can see your calculations of all the component parts for each statistic
Do people buy prefer popcorn with or without butter and does it differ if they’re at the movies or at home?
Butter No Butter Totals
Theater 92 22
Home 11 55

Expected Values – (row total/N)*column total
Theater/Butter:
Theater/No Butter:
Home/Butter:
Home/No Butter:
Observed – Expected –> squared –> divided by expected (show total for each step)
Theater/Butter:
Theater/No Butter:
Home/Butter:
Home/No Butter:
Sum of calculated values (chi-square value) =
Is it significant (alpha = .05):
Cut off value (DF = ______) –
Conclusion? :

Do people eat more chocolate in October or December?
OCTOBER Participant Ounces of Chocolate Eaten Mean Deviance Score Deviance Score Squared
1 30
2 22
3 50
4 55
5 60
6 55
7 44
8 22
9 33
10 55
11 87
12 48
13 41
14 25
15 34
16 39
17 11
18 44
19 43
20 60
Mean = Sum of Squares =

Sum of Square/N = _________- This is the VARIANCE
Square root of the VARIANCE = __________ = This is the Standard Deviation

December Participant # Ounces of Chocolate Eaten Mean Deviance Score Deviance Score Squared
1 22
2 11
3 18
4 14
5 13
6 18
7 22
8 0
9 10
10 8
11 17
12 18
13 19
14 14
15 13
16 18
17 15
18 23
19 27
20 35
Mean = Sum of Squares =

Sum of Square/N = ________ – This is the VARIANCE
Square root of the VARIANCE = __________ = This is the Standard Deviation

Mean (October) =
Mean (December) =
Subtract the two means = (this is your MEAN DIFFERENCE)*
Divide the October VARIANCE by N =
Divide the December VARIANCE by N =
Add these two scores together = ______ – >take the square root of this number = ____(**)
Divide MEAN DIFFERENCE* by the number above(**) – ________ – this is your t value!
Degrees of Freedom = N-2 – DF = __________ Find on crit value table – compare!
Do we REJECT or ACCEPT the null hypothesis (reject = means are different) ________________
Conclusion? :
T- Test Formulas

S2 = SD2

df = N – 2