AP Stats Inference

Margin of error equals:

• Critical Value x Standard Error

• z*

• 1.96

• Standard Error

When p-value is greater than alpha we:

• Accept Ho

• Accept Ha

• Fail to reject Ho

• Reject Ho

What's the appropriate interpretation of the slope of the regression line?

• For every additional 0.61 hours of growth, the culture is predicted to weight 1 more gram.

• For every additional hour of growth, the culture is predicted to weigh 0.61 more grams.

• For every additional hour of growth, the logarithm of the culture's weight in grams is predicted to increase by 0.61.

• At the beginning of the experiment, the logarithm of the culture's weight in grams was approximately 0.61 ounces.

What does r² stand for?

• correlation coefficient

• coefficient of determination

• slope of the line of best fit (LOBF) for a sample

• slope of the line of best fit (LOBF) for a population

Which is TRUE?
I.  Random scatter in the residuals indicates a linear model.
II.  If two variables are very strongly associated, then the correlation between them will be near 1 or -1.
III.  Changing the units of measurement for x or y changes the correlation coefficient.

• I only

• II only

• I and II only

• I, II and III

Given the image of linear regression computer output, what would the correlation coefficient be?

• .922

• .96

• -0.03761

• 28.37

To determine property taxes, Florida reappraises real estate every year, and the county appraiser's website lists the current "fair market value" of each piece of property. Property usually sells for somewhat more than the appraised market value. We collected data on the appraised market values x and the actual selling prices y (in thousands of dollars) of a random sample of 16 condominium units in Florida. We checked that the conditions for inference about the slope of the population regression line are met. Here is part of the Minitab output from a least-squares regression analysis using these data. The equation of the least-squares regression line for predicting selling price from appraised value is

What is the equation of the LSRL

• y = 0.2 + 0.32x

• y = -0.97 + 175.3x

• y = 0.97 - 175.553x

• y = -175.554 + 0.097x

Is there a relationship between reaction time and age? A statistics student measures the reaction time of 12 subjects by measuring how far a yardstick drops, in inches, before a subject catches it between his or her thumb and forefinger (a high number thus indicates a slow reaction time). The student plans to use linear regression to see if reaction time can be predicted by the age of the subject. Output from a computer regression analysis is given below. The equation of the least-squares regression line is

• 
• 
• 

The computer output is used to predict helicopter flight time from drop height.  Which is the correct equation for this relationship?

• (Time) = -0.03761+0.0057244(drop height)

• (time) = -0.03761+0.05838(drop height)

• (height)=-0.03761+0.0057244(time)

• (height)=0.0057244-0.03761(time)