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Bivariate Data. Chapters 7-10. Formulas. Predicted Response Variable = B o + B 1 ( Explanatory Variable ). When analyzing a scatterplot you will want to note direction, strength, form, and outliers. Key Players: - PowerPoint PPT Presentation
Bivariate Data
Chapters 7-10
Formulas
Predicted Response Variable = Bo + B1(Explanatory Variable)
x
y
S
Srb 1 xbyb 10
x
y
S
Sr
When analyzing a scatterplot you will want to note direction, strength, form, and outliers.
Key Players:
r: Correlation – tells strength and direction of a linear relationship
r2: Coefficient of determination – tells the amount of variabilityin the Response variable explained by the LSRL or by the ExplanatoryVariable
bo: y-intercept – tells the starting point or the amount when the Explanatory variable = 0
b1: Slope – Rate of change, tells how much the Response VariableChanges when the Explanatory Variable goes up by 1 (or by the unitsIndicated on the x-axis)
Interpreting r, r2, b0, and b1
r = .99: Strong, positive relationship between time in hours and log of populationr2 = .982: 98.2% of the variation in log of population is explained by hours or by the LSRLb1 = .115: As hours increases by 1, log of pop will increase by about .115
b0 = .322: When hours = 0, log predicted pop will equal .322, substituting 0 into
equation we get 103.22 = about 2.1 or predicted pop = about 2.1 thousand