In: Statistics and Probability
The hypothesis being tested is:
H0: Plain M&Ms follow the stated distribution
Ha: Plain M&Ms does not follow the stated distribution
| observed | expected | O - E | (O - E)² / E | |
| Red | 63 | 89.440 | -26.440 | 7.816 |
| Orange | 155 | 137.600 | 17.400 | 2.200 |
| Yellow | 90 | 89.440 | 0.560 | 0.004 |
| Green | 101 | 137.600 | -36.600 | 9.735 |
| Blue | 181 | 137.600 | 43.400 | 13.689 |
| Brown | 98 | 96.320 | 1.680 | 0.029 |
| 688 | 688.000 | 0.000 | 33.473 | |
| 33.47 | chi-square | |||
| 5 | df | |||
| 3.03E-06 | p-value |
The p-value is 0.0000.
Since the p-value (0.0000) is less than the significance level (0.05), we can reject the null hypothesis.
Therefore, we can conclude that Plain M&Ms does not follow the stated distribution.
A different significance level would not have changed the conclusion.
3. Use the distribution below to test that Halloween Skittles
follow the stated distribution. Discuss your choice of significance
level. Would a different significance level have changed your
conclusion?
Skittles states the following distribution:
Red = 18%, Orange = 22%, Green = 17%, Blue = 20%, Purple = 22%,
Other (Zombie color) = 1%
| observed frequencey, O | expected proportion | expected frequency,E | (O-E) | (O-E)²/E | |
| 63 | 0.180 | 123.84 | -60.84 | 29.889 | |
| 155 | 0.220 | 151.36 | 3.64 | 0.088 | |
| 90 | 0.170 | 116.96 | -26.96 | 6.214 | |
| 101 | 0.200 | 137.60 | -36.60 | 9.735 | |
| 181 | 0.220 | 151.36 | 29.64 | 5.804 | |
| 98 | 0.010 | 6.880 | 91.12 | 1206.810 |
chi square test statistic,X² = Σ(O-E)²/E =
1258.541
level of significance, α= 0.01
Degree of freedom=k-1= 6 -
1 = 5
P value = 0.0000 [ excel function:
=chisq.dist.rt(test-stat,df) ]
Decision: P value < α, Reject Ho
Therefore, we can conclude that Plain M&Ms does not follow the stated distribution.
A different significance level would not have changed the conclusion.