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AP STATS UNIT 2
| Term | Definition |
|---|---|
| 1. | Scatterplot with a y^ overlay in context |
| 1 description | make the scatterplot and add equation + equation in context |
| 2. | correlation coefficient (r) in context |
| 2 description | The correlation coefficient r = ____ indicates a (weak/moderate/strong) (positive/negative) linear relationship between (var 1) and (var 2) in (Measurement/description) |
| 3. | coefficient of determination (r^2) in context |
| 3 description | The coefficient of determination r=__ indicates that approx (r in % form) of the variation using (var 1) to predict (var 2) is accounted for by the least squares regression line while using (var 1) to predict (var 2), the other (100-r%) is unaccounted for |
| 4. | Slope of the least-squares regression (b) in context |
| 4 description | The predicted (measure) goes up/down (#) every ___ (measure) |
| 5. | residuals |
| 5 description | find residual --> L2 - Y1(L1) Scatterplot --> x: L1 y: L3 |
| 6. | residual plot with analysis |
| 6 description first sentence | The residual plot appears (homo/hetero) in nature. |
| 6 description homo | This shows that the residuals are evenly and randomly scattered about a mean of 0 indicating constant error variants, signaling a reliable model. |
| 6 description hetero | This shows a non-constant spread indicating a violation of regression assumptions and can lead to a unrealiable statistical inference |
| 7. | standard deviation of the residuals (SDres) in context |
| 7 description | SDres = ___ indicates that the actual (var) is typically (SD) away from the number predicted by the least squares regression line with x = (x-variable) |
| 8. | outliers and influential points (high-leverage) |
| 8 description outlier beginning + correlation | Point # is an outlier because it has a large residual. The point for point # makes the correlation closer to 0 because it decreases the strength of what would otherwise be a moderately strong/weak positive/negative association. |
| 8 description outlier slop + y-int. | Because this point's x coordinate is very close to mean x, it won't influence the slope very much. However, it will make the y-intercept increase/decrease because its y coordinate is so large compared to the rest of the values. |
| 8 description influential beginning + correlation | Point # is a influential point because it has a much larger x-value than the other points. Because the point for point # is in the pos/neg linear pattern formed by most of the data values, it will make the correlation closer to 1. |
| 8 description influential slope | Also, because the point is likely to be below the least-squares regression line, it will "pull down" the line on the right side, making the slop closer to 0. |