Understand Confidence Intervals and Sample Size

Today lets understand about Confidence Intervals and Sample Size

The main objective of this section is to explain the basics of estimating a parameter such as a mean, proportion, or variance.

Sample measures (i.e., statistics) are used to estimate population measures (i.e., parameters). For example, a sample mean is used to estimate a population mean. A sample proportion is used to estimate a population proportion. These statistics are called estimators.

Suppose a college president wishes to estimate the average age of students attending classes this semester. The president could select a random sample of 100 students and find the average age of these students, say, 22.3 years. From the sample mean, the president could infer that the average age of all the students is 22.3 years. This type of estimate is called a point estimate.

Another example might be that a restaurant owner wishes to see what proportion of Americans purchase take-out food every day. A random sample of 1,000 individuals shows that 0.11 or 11% of the people in the sample purchase take-out food every day. The same is true of other statistics. These types of estimates are called point estimates.

A point estimate is a specific numerical value estimate of a parameter. The best point estimate of the…