TABLE 12-4
A computer used by a 24-hour banking service is supposed to randomly assign each transaction to one of 5 memory locations. A check at the end of a day's transactions gave the counts shown in the table to each of the 5 memory locations, along with the number of reported errors.

The bank manager wanted to test whether the proportion of errors in transactions assigned to each of the 5 memory locations differ.
-Referring to Table 12-4, the degrees of freedom of the test statistic is
A) 4.
B) 8.
C) 10.
D) 448.

Question

TABLE 12-4
A computer used by a 24-hour banking service is supposed to randomly assign each transaction to one of 5 memory locations. A check at the end of a day's transactions gave the counts shown in the table to each of the 5 memory locations, along with the number of reported errors.
  
The bank manager wanted to test whether the proportion of errors in transactions assigned to each of the 5 memory locations differ.
-Referring to Table 12-4, the degrees of freedom of the test statistic is
A) 4. 
B) 8. 
C) 10. 
D) 448.

Quizplus · Accepted Answer

The degrees of freedom for the test statistic is the number of independent observations minus the number of parameters estimated. In this case, there are 449 observations and 1 parameter estimated (the mean). Therefore, the degrees of freedom is 449 - 1 = 448.

TABLE 12-4 A Computer Used by a 24-Hour Banking Service Is Supposed