In: Statistics and Probability
Q 6 A STUDY WAS CONDUCTED TO
DETERMINE IF THERE IS A SIGNIFICANT RELATIONSHIP BETWEEN THE
FREQUENCY OF MEAT SERVED AS A MAIN MEAL PER MONTH FOR INDIVIDUALS
LIVING IN THE FOUR SECTIONS OF THE UNITED STATES. A QUESTIONAIRE
WAS ADMINISTERED TO A RANDOM SAMPLE OF 400 FAMILIES AND THE RESULTS
ARE SUMMARIZED BELOW
FREQUENCY OF
MEAT AS A MAIN MEAL PER MONTH
LIVING AREA LESS THAN
11 11 TO 20 MORE THAN 20 ROW
TOTALS
EASTERN 46
36 20 102
SOUTH 40
40 26 106
WESTERN 16
38 38 92
NORTH 25
36 39 100
COLUMN TOTALS
127 150 123 400
DO THESE SAMPLE RESULTS INDICATE
THAT THERE IS A SIFNIFICANT RELATIONSHIP BETWEEN THE FREQUENCY OF
MEAT SERVED AS A MAIN MEAL PER MONTH AND GEOGRAPHIC LIVING AT ALPHA
= 0.01
First we compute the expected frequency for each of the 12 cells
here as:
Ei = (Sum of column i)*(Sum of row i) / Grand Total
These are computed in the circular brackets below as:
The chi square test statistic contribution here is computed as:
These are given in the square bracket in the given table.
These are summed to obtain the chi square test statistic here as:
Degrees of freedom here is computed as:
Df = (num of rows - 1)*(Num of columns - 1) = (4 - 1)*(3 - 1) =
6
Therefore the p-value is now obtained from the chi square distribution tables here as:
As the p-value here is 0.000235 < 0.01 which is the level of significance, therefore the test is significant here and we can reject the null hypothesis here. Therefore we have sufficient evidence here that the two variables are associated here that is not independent.