Two Types of Estimate

1. Point Estimate- a specific numerical value estimate of a parameter.

    Example: 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 of these students, say 19.3 years. From the sample mean, the president could infer that the average age of all the students in 19.3 years.
    Sample mean will be for the most part, somewhat different from the population mean due to sampling error.

2. Interval Estimate- range of values used to estimate the parameter. This estimate may or may not contain the values of the parameter being estimated.

    Example: An interval estimate for the average of all students might be 17.9 < m < 18.7 or 18.3 + 0.3 years.
  
    Either the interval contains the parameter or it does not. A degree of confidence therefore is assigned before an interval estimate is made.



J.Santillan