# Statistics Lab Report 2611

**Topics:**Prediction interval, Confidence interval, Sample size

**Pages:**3 (691 words)

**Published:**February 25, 2013

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Objectives

The purpose of this lab intends to explain the process and impacts of confidence and prediction interval techniques and procedures by learning through online tutorials, examples, and quizzes. Procedures

This lab was conducted in a controlled, computer environment with access to SAS software and applications. Instructions for the lab were provided in .pdf form and included procedures for accessing private applications in SAS. Additionally, tutorials and quizzes were administered using an applet available at http://www.wpi.edu/Academics/ATC/Collaboratory/LOs/Gagnon/PItutor/index.html and http://www.wpi.edu/Academics/ATC/Collaboratory/LOs/Gagnon/CIpQuiz/index.html. Prediction Intervals

A tutorial was given to help explain the process and purpose of prediction intervals. Following the tutorial, a quiz was taken. The results from the quiz are shown in Figure 1.

Figure 1: Results from online quiz #1.

The purpose of a prediction interval is to tell you where you can expect the next data point to be. SAS computes the prediction interval using equation 5.11, shown below. Ynew-σYnew-Ynewtn-1,1+L2,Ynew+σ(Ynew-Ynew)tn-1,1+L2,

The assumptions of this formula are that the {∈i} are independent N(0,σ2) random variables. Following the instructions from the lab report, SAS was used to build a data containing the measurements of the speed of light. Parameters for the application are C = 0.90. The results of this application are shown in Figure 2.

Figure 2: Prediction Interval using SAS with application SASDATA.SOL. C = 0.90 The width of the prediction interval is 2.9996 - 2.9972 = .0024. The width of the confidence interval is 2.9985 – 2.9983 = .0012. The width of the prediction interval is exactly twice as large (wide) as the confidence interval. If the confidence interval is increased to C = 0.95 (95%), the result is an increase in...

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