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Basic Analysis and Graphing - SAS

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Chapter 4 Performing Bivariate <strong>Analysis</strong> 105<br />

Fit Line <strong>and</strong> Fit Polynomial<br />

Figure 4.13 Examples of Parameter Estimates Reports for Linear <strong>and</strong> Polynomial Fits<br />

Table 4.7 Description of the Parameter Estimates Report<br />

Term<br />

Estimate<br />

Std Error<br />

t Ratio<br />

Prob>|t|<br />

Lists the name of each parameter in the requested model. The intercept is a constant term<br />

in all models.<br />

Lists the parameter estimates of the linear model. The prediction formula is the linear<br />

combination of these estimates with the values of their corresponding variables.<br />

Lists the estimates of the st<strong>and</strong>ard errors of the parameter estimates. They are used in<br />

constructing tests <strong>and</strong> confidence intervals.<br />

Lists the test statistics for the hypothesis that each parameter is zero. It is the ratio of the<br />

parameter estimate to its st<strong>and</strong>ard error. If the hypothesis is true, then this statistic has a<br />

Student’s t-distribution.<br />

Lists the observed significance probability calculated from each t-ratio. It is the probability<br />

of getting, by chance alone, a t-ratio greater (in absolute value) than the computed value,<br />

given a true null hypothesis. Often, a value below 0.05 (or sometimes 0.01) is interpreted<br />

as evidence that the parameter is significantly different from zero.<br />

To reveal additional statistics, right-click in the report <strong>and</strong> select the Columns menu. Statistics not shown<br />

by default are as follows:<br />

Lower 95%<br />

Upper 95%<br />

The lower endpoint of the 95% confidence interval for the parameter estimate.<br />

The upper endpoint of the 95% confidence interval for the parameter estimate.<br />

Std Beta The st<strong>and</strong>ardized parameter estimate. It is useful for comparing the effect of X variables that are<br />

measured on different scales. See “Statistical Details for the Parameter Estimates Report” on page 126.<br />

VIF<br />

The variance inflation factor.<br />

Design Std Error The design st<strong>and</strong>ard error for the parameter estimate. See “Statistical Details for the<br />

Parameter Estimates Report” on page 126.

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