Question

wholesaler has recently developed a computerized sales invoicing system. Prior to implementing this system, a manual system was used. The distribution of the number of errars per invoice for the manual system is as follows: Errors per Invoice Percentage of Invoices More Than 3 1% 2 87% 3% After implementation of the computerized system, a random sample of 500 invoices gives the following error distribution: Errors per Invoice Number of Invoices More Than 3 1 479 1t 1- 087 4506 435 479 22.5000 0.08 40 10 1,8000 32000 001 35.21730 Chi-Square p-value 00000001096 (a) Show that it is appropriate carry out a chi-square test using these data. Each Ez 9 48 (b) Use the Excel output shown above to detemine whether the error percentages for the computerized system differ from those for the manual system at the .05 level of significance. What do you conclude? H: Conclude systems difter Reject

Answer 1

a)

each E i >=5

b)

as p value is significantly low:

reject Ho ; conclude systems differ.