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AP Stats ch 7 Flashcards

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14971239352modelan equation or formula that simplifies and represents reality0
14971244239linear modelis an equation of a line. To interpret a linear model, we need to know the variables (along with their W's) and their units.1
14971266279predicted variablethe value of y found for a given x-value in the data. A predicted value is found by substituting the x value in the regression equation. The predicted values are the values on the fitted line; the points (x,y) all lie exactly on the fitted line.2
14971346286Residualsare the differences between data values and the corresponding values predicted by the regression model ----or more generally values predicted by any model.3
14971389014Leasts squaresThe leasts squares criterion specifies the unique line that minimizes the variance of the residuals or equivalently, the sum of the squared residuals.4
14971420936regression to the meanBecause the correlation is always less than 1.0 in magnitude, each predicted y-hat tends to be fewer standard deviations from its mean than its corresponding x was from its mean.5
14971443263regression lineThe particular linear equation that satisfies the least squares criterion, often called the line of best fit.6
14971448414line of best fit7
14971474381slopethe slope b1 gives a value in "y-units per x-units." Changes of one unit in x are associated with changed of b1, units in predicted values of y. The slope can be found by8
14971519393interceptb0 gives a starting value in y-units. Its the y value when x is 09
14971543837Sestandard deviation of residuals10
14971560940R2The square of the correlation between x and y gives the fraction of the variability of y accounted for by the least squares linear regressions on x.11
14971596756Does the Plot thicken? ConditionThe scatterplot or residuals plot should consistent (vertical) spread in y-values.12

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