‘A/B’ quality test or Z-test for the mean of a distribution
Some company would like to compare quality of service for call center workers in two different locations A and B. The service quality will be estimated as a quantity of solves issues during a day. The company randomly select 30 workers from call center A and 30 from B. So, average completed issues in A was 750 with standard deviation 20. And average completed issues in B was 780 with standard deviation 25. Requirement to estimate : Is the call center B shows statistically significant better service quality at statistical significance level 5%? We will use Z-test ( Wikipedia ) to compare two average of samples. The standard deviation is known and we assume samples with Normal distribution. Note: Z-test is valid for sample size from 30. Use Student's t-test instead for smaller sample sizes. Null hypothesis H0 - mean of A is equals to the mean of B. Call center A shows the same service quality as the call center B. Alternative hypothesis H1 - mean of A is NOT equals to the mean of B...