242 PART 5 Looking for Relationships with Correlation and Regression

»

» ^{Residual information: As a reminder, the residuals are the observed}

outcome values minus predicted values coming from the model. Under

Residuals, the minimum, first quartile, median, third quartile and maximum

are listed (under the headings Min, IQ, Median, 3Q, and Max, respectively).

The maximum and minimum indicate that one observed SBP value was

17.8 mmHg greater than predicted by the model, and one was 15.4 mmHg

smaller than predicted.»

» ^{Regression or coefficients table: This is presented under Coefficients:, and}

includes a row for each parameter in the model. It also includes columns for

the following:

• ^{Estimate: The estimated value of the parameter, which tells you how much}

the outcome variable changes when the corresponding variable increases

by exactly 1.0 unit, holding all the other variables constant. For example, the

model predicts that if all participants have the same weight, every addi-

tional year of age is associated with an increase in SBP of 0.84 mmHg.

• ^{Standard error: The standard error (SE) is the precision of the estimate,}

and is in the column labeled Std. Error. The SE for the Age coefficient is

0 52

.

mmHg per year, indicating the level of uncertainty around the

0.84 mmHg estimate.

• ^{t value: The t value (which is labeled t value) is the value of the parameter}

divided by its SE. For Age, the t value is 0 8446 0 5163

.

/ .

, or 1.636.

• ^{p value: The p value is designated Pr(>|t|) in this output. The p value}

indicates whether the parameter is statistically significantly different from

zero at your chosen α level (let’s assume 0.05). If p 0.05, then the

predictor variable is statistically significantly associated with the outcome

after controlling for the effects of all the other predictors in the model. In

FIGURE 17-2:

Output from

multiple

regression using

the data from

Table 17-2.