An estimate of a population parameter may be expressed in two ways:
- Point Estimate: A point estimate of a population parameter is a single value of a statistic. For example, the sample mean x¯ is a point estimate of the population meanμμ. Similarly, the sample proportion p is a point estimate of the population proportion P.
- Interval estimate: An interval estimate is defined by two numbers, between which a population parameter is said to lie. For example, a<x¯¯¯<ba<x¯<b is an interval estimate of the population meanμμ. It indicates that the population mean is greater than aa but less thanb