Question

The engineer, JJ, works for an electronic firm. She realizes that 4.5% of all integrated chips produced in her department are defective. She hired a consulting firm to give her advice on how to reduce the production of defective chips. The new plans were implemented. Now JJ wants to confirm that production of defectives had been reduced. How will she collect data and what statistical analysis she will do?

Answer 1

After the plan is implemented, she will sample integrated chips produced in her department randomly, where sample size would be big enough (>30)

Then she will apply hypothesis test to see if the implemented plan reduced defective chip proportion.

Explanation:

• Null hypothesis would assume defective rate as 4.5%

• Alternate hypothesis would assume defective rate as less than 4.5%.

• Assuming the null hypothesis is true, z-statistic and p-value of the sample mean will be calculated and compared to p-critical in a given significance level.
• If the p-value is small enough then the null hypothesis is rejected in favor of alternate hypothesis