In: Math
7.16 How do you position yourself when you are going to sleep? A website tells us that 41% of use start in the fetal position, another 28% start on our side with legs straight, 13% start on their back, and 7% on their stomach. The remaining 11% have no standard starting sleep position. If a random sample of 1000 people produces the frequencies in the table below, should you doubt the proportions given in the article in the website? Show all the details of the test, and use a 5% significance level.
Sleep Position |
Frequency |
Fetal |
391 |
Side, legs straight |
257 |
Back |
156 |
Stomach |
89 |
None |
107 |
Total |
1000 |
null hypothesis Ho: proportion of people position in sleep is as stated given in the article in the website
Alternate hypothesis Ho: proportion of people position in sleep is not as stated given in the article in the website
degree of freedom =categories-1= | 4 | ||||
for 0.05 level and 4 degree of freedom :rejection region = | 9.488 | ||||
applying chi square goodness of fit test: |
% *students | pearson | ||||
relative | observed | Expected | residual | Chi square | |
category | frequency(p) | Oi | Ei=total*p | R2i=(Oi-Ei)/√Ei | R2i=(Oi-Ei)2/Ei |
Fetal | 0.410 | 391.000 | 410.0000 | -0.94 | 0.880 |
Side, legs straight | 0.280 | 257.000 | 280.0000 | -1.37 | 1.889 |
Back | 0.130 | 156.000 | 130.0000 | 2.28 | 5.200 |
Stomach | 0.070 | 89.000 | 70.0000 | 2.27 | 5.157 |
None | 0.110 | 107.000 | 110.0000 | -0.29 | 0.082 |
total | 1.000 | 1000 | 1000 | 13.2087 |
test statistic X2 = | 13.2087 |
since test statistic falls in rejection region we reject null hypothesis | ||||||
we have sufficient evidence to conclude that proportion of people position in sleep is not as stated given in the article in the website |