Popcorn Experiment
An experiment is conducted on the effect of cooking time on the volume of microwave
popcorn. Uncooked popcorn kernels contain moisture. When the popcorn is heated the
moisture turns to a gas causing the popcorn to pop. The more the kernels pop but do not
burn the better the quality. Therefore better quality popcorn would produce a larger
volume of popped, but unburned, kernels. Eighteen snack bags of Pop Secret Home-style
microwave popcorn are purchased. All bags are labeled as containing 1.5 ounces
(approximately 42.5 grams). Six bags are randomly assigned to each of three cooking
times: 1.25 minutes, 1.75 minutes and 2.25 minutes. The order of popping and
determining the volume of popped but not burned popcorn is also randomized. All bags
are popped in the same microwave at full power. The microwave is allowed to “cool
down” and all moisture is wiped up after every bag is popped. Volume is measured in
centiliters (cl).
Mean, Yi
Std. Dev., s i
1.25 minutes
62
91
67
51
64
91
71.0
Cooking time
1.75 minutes
119
125
143
148
121
136
132.0
2.25 minutes
125
119
148
136
148
128
134.0
16.41
12.01
12.15
1
2
Multiple Comparisons
Oneway Analysis of Volume (cl) By Time (min)
Means Comparisons
Comparisons for each pair using Student's t
t
2.13145
Alpha
0.05
Abs(Dif)-LSD
2.25
1.75
1.25
2.25 -16.8611 -14.8611 46.13893
1.75 -14.8611 -16.8611 44.13893
1.25 46.13893 44.13893 -16.8611
Positive values show pairs of means that are significantly different.
Level
2.25 A
1.75 A
1.25
B
Mean
134.00000
132.00000
71.00000
Levels not connected by same letter are significantly different.
Level
2.25
1.75
2.25
- Level
1.25
1.25
1.75
Difference
63.00000
61.00000
2.00000
Std Err Dif
7.910612
7.910612
7.910612
Lower CL
46.1389
44.1389
-14.8611
Upper CL
79.86107
77.86107
18.86107
p-Value
<.0001*
<.0001*
0.8038
Comparisons for all pairs using Tukey-Kramer HSD
q*
2.59747
Alpha
0.05
Abs(Dif)-LSD
2.25
1.75
1.25
2.25 -20.5476 -18.5476 42.45242
1.75 -18.5476 -20.5476 40.45242
1.25 42.45242 40.45242 -20.5476
Positive values show pairs of means that are significantly different.
Level
2.25 A
1.75 A
1.25
B
Mean
134.00000
132.00000
71.00000
Levels not connected by same letter are significantly different.
Level
2.25
1.75
2.25
- Level
1.25
1.25
1.75
Difference
63.00000
61.00000
2.00000
Std Err Dif
7.910612
7.910612
7.910612
Lower CL
42.4524
40.4524
-18.5476
Upper CL
83.54758
81.54758
22.54758
p-Value
<.0001*
<.0001*
0.9655
3
Plot of residuals versus treatment groups
Distribution of Residuals
Residual
Mean
Std Dev
N
0
12.870395
18
Residuals
4