Statistics

Lab - Chapter 9 (Two Sides!)

Regression and Correlation

1. Using string, measure the diameter and circumference of at least 15 circles of different sizes.You need to measure both and pretend that you don't know the relationship between the diameter and circumference, which is pi.We are going to estimate this relationship using regression. Let x represent the diameter and y represent the circumference, this is important to not mix up x and y.Your ordered pairs will be of the form (diameter, circumference).Record the data here and include the name of the object you measured.For example: coffee cup, diameter (x) 3in and circumference (y) 8.9in. :

Please be sure to measure both the diameter AND the circumference. Do not estimate the circumference using the known slope parameter, pi.I will check your measurements to make sure you didn't just multiply the diameter by pi or 3.14.

1. Construct a scatter plot on StatCrunch or Minitab, graph below (you can cut and paste or graph NEATLY by hand:

1. For the paired data above, find the correlation coefficient, r, and determine if r is significant at = 0.05 and = 0.01 using the critical values in Table 11.

1. If r is significant, find the regression equation (using technology). Is your slope close to the true parameter of pi?

1. If r is significant, use the regression equation to predict what the circumference would be for a circle with a diameter of 6 inches.