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Practice Test 2
... a. increase of $4 in advertising is associated with an increase of $4,000 in sales b. increase of $1 in advertising is associated with an increase of $4 in sales c. increase of $1 in advertising is associated with an increase of $34,000 in sales d. increase of $1 in advertising is associated with an ...
... a. increase of $4 in advertising is associated with an increase of $4,000 in sales b. increase of $1 in advertising is associated with an increase of $4 in sales c. increase of $1 in advertising is associated with an increase of $34,000 in sales d. increase of $1 in advertising is associated with an ...
Least Squares Regression Line
... Plot the residuals against the yhats. How does this residual plot compare to the previous one? ...
... Plot the residuals against the yhats. How does this residual plot compare to the previous one? ...
Introduction to Elementary Statistical Methods for the Study of Behavior
... (for ANOVA) a posteriori comparisons (e.g., Tukey's HSD, Fischer's LSD). 18. Analyze and explain the advantages of multigroup and factorial research designs in comparison to single factor and two-group designs. 19. Measure and apply correlation and regression by (a) defining and differentiating thes ...
... (for ANOVA) a posteriori comparisons (e.g., Tukey's HSD, Fischer's LSD). 18. Analyze and explain the advantages of multigroup and factorial research designs in comparison to single factor and two-group designs. 19. Measure and apply correlation and regression by (a) defining and differentiating thes ...
Linear Regression t
... If the data are scattered to about the same extent as we move from left to right, we can say that the equal variance assumption is met. Some people call this visual inspection the Does the plot thicken? condition. That is, do the residuals get closer together in part of the graph? In our example th ...
... If the data are scattered to about the same extent as we move from left to right, we can say that the equal variance assumption is met. Some people call this visual inspection the Does the plot thicken? condition. That is, do the residuals get closer together in part of the graph? In our example th ...
Coefficient of determination
In statistics, the coefficient of determination, denoted R2 or r2 and pronounced R squared, is a number that indicates how well data fit a statistical model – sometimes simply a line or a curve. An R2 of 1 indicates that the regression line perfectly fits the data, while an R2 of 0 indicates that the line does not fit the data at all. This latter can be because the data is utterly non-linear, or because it is random.It is a statistic used in the context of statistical models whose main purpose is either the prediction of future outcomes or the testing of hypotheses, on the basis of other related information. It provides a measure of how well observed outcomes are replicated by the model, as the proportion of total variation of outcomes explained by the model (pp. 187, 287).There are several definitions of R2 that are only sometimes equivalent. One class of such cases includes that of simple linear regression where r2 is used instead of R2. In this case, if an intercept is included, then r2 is simply the square of the sample correlation coefficient (i.e., r) between the outcomes and their predicted values. If additional explanators are included, R2 is the square of the coefficient of multiple correlation. In both such cases, the coefficient of determination ranges from 0 to 1.Important cases where the computational definition of R2 can yield negative values, depending on the definition used, arise where the predictions that are being compared to the corresponding outcomes have not been derived from a model-fitting procedure using those data, and where linear regression is conducted without including an intercept. Additionally, negative values of R2 may occur when fitting non-linear functions to data. In cases where negative values arise, the mean of the data provides a better fit to the outcomes than do the fitted function values, according to this particular criterion.