# RESEARCH METHODOLOGY

## STATISTICAL TECHNIQUES AND TOOLS

### CONFIDENCE INTERVALS

 Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
A quality control specialist at a glass factory must estimate the mean clarity rating for a new batch of glass using a sample of 18 glass sheets from the batch. Past investigations show that clarity ratings are normally distributed. The specialist decides to use a t-distribution rather than a z-distribution because ____
 A The t distribution is more accurate than a z distribution. B Clarity ratings for the entire bacth are normally distributed. C The t-distribution will create a narrower interval than z. D The standard deviation for the population is unknown.
Explanation:

Detailed explanation-1: -The t-distribution is used in a confidence interval for a mean when the actual standard error is not known. The t-distribution allows the calculation of confidence intervals for means for small samples when the population variance is not known, regardless of the shape of the distribution in the population.

Detailed explanation-2: -The t-distribution is a type of normal distribution that is used for smaller sample sizes. Normally-distributed data form a bell shape when plotted on a graph, with more observations near the mean and fewer observations in the tails.

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