In: Statistics and Probability
Use the provided contingency table and expected frequencies. At alpha equals 0.01, test the hypothesis that the variables are independent. What is the test statistic?
Result | stretched | not stretched |
injury | 16(20.979) | 24(19.021) |
No injury | 209(204.021) | 180(184.979) |
The following is the table for observed and expected frequency
Result | stretched | not stretched |
injury | 16(20.979) | 24(19.021) |
No injury | 209(204.021) | 180(184.979) |
Observed Frequency(O) | Expected Frequency ( E) | ( O-E)^2 | ( O-E)^2/E |
16 | 20.979 | 24.790441 | 1.181678869 |
24 | 19.021 | 24.790441 | 1.303319542 |
209 | 204.021 | 24.790441 | 0.121509261 |
180 | 184.979 | 24.790441 | 0.134017597 |
429 | 429 | 99.161764 | 2.740525269 |
= 2.74
Null hypothesis: the events are independent
Alternate hypothesis: the events are dependent
The critical value at df = 4 - 1 = 3 and alpha = 0.01 is given by = 11.345
Reject the null hypothesis if >
Here, = 2.74 < = 11.345
Hence do not reject the null hypothesis
The events are independent