Confidence interval

Question

1.The reason that we want to develop a confidence interval for the population mean is because...

(Two correct answers)

1. the chance that the sample mean is equal to the population mean is zero.

2. the sampling distribution of the sample mean is normally distributed.

3. the standard error of the sample mean is an efficient estimate of the population error.

4. the sample mean is an efficient estimate of the population mean.

5. the value of the sample mean varies from sample to sample.

2.A manufacturing company produces electric insulators. You define the variable of interest as the strength of the insulators. If the insulators break when in use, a short circuit is likely. To test the strength of the insulators, you carry out destructive testing to determine how much force is required to break the insulators. You measure force by observing how many pounds are applied to the insulator before it breaks. You collect the force data for 30 insulators selected for the experiment and find out that the mean force is 1670. The value 1670 is:

1. a point estimate

2. a statistic

3. an interval estimate

4. a confidence interval

5. a parameter

Answer 1

Question #1 & #2

1. Confidence Interval - How much confidence do you have in being right or wrong? 95% confidence interval means 95% chance of being right with a 5% chance of being wrong.
2. The null hypothesis is often ZERO.
3. when trying to make inferences on a sample of data, uncertainty arises. True values should fall within a range that the confidence level depicts.