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A Step by Step Guide for SPSS and Exercise Studies

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128 Statistical tests<br />

Figure 39<br />

first criterion is based on whether the variables have reached a certain<br />

probability level of the F value. The second criterion is based on whether the<br />

variables have reached a certain F value. Most regression analyses should<br />

contain a constant term. It is there<strong>for</strong>e advisable to tick the box include constant<br />

in the equation. Under Missing values you can specify a number of different<br />

ways of h<strong>and</strong>ling missing values. Exclude cases listwise deletes all cases<br />

(participants) with missing values in any of the variables in the analysis. Exclude<br />

cases pairwise deletes cases with missing values only on the pair of variables<br />

used to compute the correlation coefficient on which the regression analysis is<br />

based. Replace with mean does not delete any cases. On the contrary, it replaces<br />

all missing values of a variable with the mean score of that variable. Use the last<br />

two options to deal with missing cases when the sample size is not large enough<br />

to provide a good ratio of cases to independent variables (see the assumptions of<br />

regression analysis above). The analysis below was carried out using both males<br />

<strong>and</strong> females.<br />

The R value shows the linear association between the independent variables<br />

<strong>and</strong> the dependent variable. The R Square value indicates that 22% of the<br />

variance in the dependent variable is explained <strong>by</strong> the two independent<br />

variables. Adjusted R square represents an adjustment of the R Square value, as<br />

the latter is often overestimated in small sample sizes. Change Statistics are<br />

useful when there is more than one block of independent variables in the

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