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AP Statistics Chapter 3 Flashcards

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6714823009Response variableMeasures the outcome of a study, dependent variable, y0
6714823010Explanatory variableAttempts to explain observed outcomes, indepdent variable, x1
6714823011ScatterplotsShow the relationship betweeen two quantitive variables (bivariate data). Each individual in a data set appears as a fixed point. All data points are plotted but not connected2
6714823015Positive associationAs x increases, y increases3
6714823016Negative associationAs x increases, y decreases4
6714823018Correlation (r)Measures strength and direction ( + or - )5
6714823019Words to describe strengthStrong (when r is close to 1 or -1), moderately strong/weak, weak (when r is close to 0)6
6714823020Words to describe directionPositive, negative7
6714823021Correlation coefficientr8
6714823022r is resistant or non-resistant to outliers?Non-resistant9
6714823023If r=1Perfect positive linear slope10
6714823024If r=-1Perfect negative linear slope11
6714823025What is the units of r?r has no units12
6714823026What is the range of r?-1 < r < 113
6714823028ResidualObserved value (y) - predicted value (y "hat")14
6714823029Least squares regression line (LSRL)The line that makes the sum of the sqaures of the vertical distances of the data points from the line as small as possible. The LSRL minimizes the total area in all of the squares. AKA "prediction line"15
6714823030What point is always on the LSRL?(x¯, y¯ )16
6714823031Equation of the LSRL17
6714823032Defining x and yWhere x denotes _______ and y denotes predicted _______18
6714823033If residual is positive...residual = (y) - (y "hat") The predicted y was less than the observed y Prediction was an underestimate19
6714980634If residual is negative...residual = (y) - (y "hat") The predicted y (y "hat") was greater than the observed y Prediction was an overestimate20
6714823053If residual = 0y - yˆ= 0 y = yˆ Prediction was accurate21
6714823034b1Slope of the LSRL22
6715018757b0y-intercept of the LSRL, the predicted y when x=023
6714823035Interpretation of the slope of the LSRLFor every one unit increase in ___(x)___ the predicted ___(y)___ increases/decreases on average by ___(b)___ units24
6714823038Coefficient of determinationIs the proportion of the variation in the values of y that is explained by the LSRL25
6714823039Coefficient of determination26
6714823041r² measures..."how good the LSRL is at predicting y"27
6714823045Interpretation of coefficient of determinationr² % of the variation in ___(y)___ is accounted for by the LSRL28
6714823046r² > ?0 (therefore, always positive)29
6714823047r is negative or positive?It can be both30
6714823048The sign of r matches the sign of...b1 (slope of the LSRL)31
6715078644Residual PlotWhen asked if a linear model is an appropriate model for the data, you MUST examine the ...32
6714823055Residual Plot characteristic: Curved patternsThe LSRL will not be the best fit -Not linear, so a line won't be the best choice33
6714823054Residual Plot charcteristic: Idealized patternsRandom, uniform scatter of points above and below the LSRL residual34
6714823056Residual Plot characteristic: Varying spreadAs x increases, the prediction will be more accurate for some values and less accurate for others35
6714823057OutlierAn observation that lies outside the overall pattern of the other observations.36
6714823058InfluentialAn observation that if it is removed it would drastically change the result of some calculation (either r or r squared)37
6714823059R-squared adjustedNEVER USE38
6714833301AxesWhen making a graph (including a scatterplot), NEVER forget to LABEL your...39
6714858125Form, direction, and strength (IN CONTEXT)"Describing the scatterplot" means to discuss the...40

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