Contingency Tables are a 2-way classification table containing frequencies of how often things appear and can be used to determine if 2 variables are independent or are significantly associated.

Since the actuals measured may not agree with the theoretical values predicted you can use the Chi Square calculation to make the determination. Additionally, a correlation coefficient can be calculated.

## Six Sigma Black Belt Certification Contingency Table Questions:

**Question:** The following contingency table was developed for an organization.

On the basis of this information, what is the expected number of oil changes for Station 1 ?

(A) 70

(B) 76

(C) 80

(D) 100

**Answer: **80. This is a contingency table question. Lots of numbers in this table. Most of them are useless. Just take the two categories we are interested in and multiply. Then divide by the all totals.

The expected number of oil changes = all of station 1 * all oil changes / All totals = 210 * 228 / 600 = 80.