AP Statistics Unit 2

A set of bivariate data was used to create a least-squares regression line. Which of the following is minimized by the line? (A) The sum of the residuals (B) The sum of the squared residuals (C) The sum of the absolute values of the residuals (D) The influence of outliers (E) The slope

(B) The sum of the squared residuals

What is extrapolation?

Predicting data beyond the measured points.

Which of the following is the best description of a positive association between two variables? (A) The values will create a line when graphed on a scatterplot. (B) The values will create a line with positive slope when graphed on a scatterplot. (C) As the value of one of the variables increases, the value of the other variable tends to decrease. (D) As the value of one of the variables increases, the value of the other variable tends to increase. (E) All values of both variables are positive.

(D) As the value of one of the variables increases, the value of the other variable tends to increase.

The height and collar size C, both in centimeters, measured from a sample of boys were used to create the regression line c^= -94 + 0.9H. The line is used to predict collar size from height, both in centimeters, for boys' shirt collars. Which of the following has no logical interpretation in context? (A) The predicted collar size of a boy with height 140cm (B) The values in the sample (C) The values in the sample (D) The slope of the regression line (E) The C-intercept of the regression line

(E) The C-intercept of the regression line

What is an influential point?

A data point that significantly changes any part of the regression analysis.

What is a lurking variable?

A factor that was not included in the experiment but is affecting the ones that are.

Factors to consider when summarizing statistics

Center and spread of distribution - skewed/outlier: median, IQR (resistant) - symmetric data without outliers: mean, standard deviation

What is interpolation?

Determining a value from the existing values in a given data set.

A researcher in Alaska measured the age (in months) and the weight (in pounds) of a random sample of adolescent moose. When the least-squares regression analysis was performed, the correlation was 0.59. Which of the following is the correct way to label the correlation? (A) 0.59 months per pound (B) 0.59 pounds per month (C) 0.59 (D) 0.59 months times pounds (E) 0.59 month pounds

(C) 0.59

How do you calculate the residual?

actual value - predicted value