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AP Stat
Statistics Vocab
| Question | Answer |
|---|---|
| Variance | average of the squared differences of all the values from the mean. standard deviation squared. |
| Standard deviation | square root of the average of the squared differences of all the values from the mean. square root of variance |
| Skewed to the right | has a long tail on the right side or the positive side. |
| Skewed to the left | has a long tail on the left side or the negative side |
| Empirical rule | 34-13.5-2.35 68% of the values lie within one standard deviation 95% of the values lie within two standard deviations 99% of values lie within three standard deviations |
| Range | Difference between the largest and the smallest number |
| Interquartile range (IQR) | Difference between the third and first quartile |
| Simple ranking | I am top 25 out of 583 students. I am the seventh best detergent out on the market. |
| Percentile ranking | convert simple rank to a percentage |
| z-score | how many standard deviations something is from the mean |
| correlational coefficient | quantitative value of the strenght of a linear relationship. -1<r<1 |
| strongly positively associated (scatter plot) | slope is positive and all values are close to the line of best fit |
| negatively associated (scatter plot) | slope is negative |
| residual plots | plot of the difference between the actual value and the line of best fit. sum of the residuals equals zero |
| outliers | values that fall away from the overall pattern. a point is an outlier if its residual is an outlier in a set of residuals |
| influential scores | scores whose removal would sharply change the regression line. typically found on the ends of the line. |