Capintec CAPTUS 4000e - Chi-Square Test

CAPINTEC, INC. CAPTUS
®
4000e
August 22 QUALITY ASSURANCE 5-15
If no problems are found with the above items, then the efficiency of the Cs137 standard
should be re-measured. If this does not correct the problem, contact Capintec’s only
Authorized Service Center for service.
10. Select the Exit button or press Alt+E to exit and return to Figure 5-1 Quality Assurance
Main Screen.
 To print current results for record keeping, select the Print button or press Alt+P on
the Constancy Test screen after the test is completed.
 To view or print results for all of the Quality Assurance tests performed to date, select
the Print / View History button or press Alt+V (Refer to the VIEWING AND
PRINTING HISTORY section on page 5-24).
CHI-SQUARE TEST
CAUTION: Calibration is recommended before making any measurements. Refer to
the AUTO CALIBRATION section on page 5-5.
The Chi-Square Test provides a sensitive check of the overall counting performance of the
system. The software will use the 662 keV peak of your Cs137 source for the tests.
# Repetitions
0.95
0.90
0.10
0.05
5
.711
1.06
7.78
9.49
10
3.33
4.17
14.7
16.9
15
6.57
7.79
21.1
23.7
20
10.1
11.7
27.2
30.1
In the table above, you can see that for a typical 10-repetition test, the Chi-Square value
should be between 3.33 and 16.9 for 90% of the time. Therefore, it is expected to be outside
this range 10% of the time. Also, because of the statistical nature of the Chi-Squared test,
the Chi-Square values should not remain exactly the same. They are expected to vary.
The Chi-Squared test value is calculated from the following equation:
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