Warm Up The following data lists the prices of 12 different bicycle helmets along with the quality rating. Make a scatterplot of the data (price is the explanatory variable) and calculate the correlation coefficient. Do you think price is a strong indicator of the quality of a bicycle helmet? Price Quality Rating Price Quality Rating 35 65 20 61 30 60 40 55 50 54 23 47 30 47 18 43 40 42 28 41 20 40 25 32

Practice Adolescent mothers are more likely to have low birth weight babies than adult mothers. The following data, published in 2009, compares mother’s age and birth weight. Mother’s Age Birth Weight (g) Mother’s Age Birth Weight (g) 15 2289 19 3327 17 3393 17 2970 18 3271 16 2535 15 2648 18 3138 16 2897 19 3573 1) Find the equation of the LSRL and calculate r. 2) Interpret the meaning of a and b in the context of the problem. 3) What is the predicted birth weight for an 18 year old mother? 15 years old? 23 years old?

Residual Plots Residuals appear random with no pattern. Residuals have clear non-linear pattern.

Practice Adolescent mothers are more likely to have low birth weight babies than adult mothers. The following data, published in 2009, compares mother’s age and birth weight. Mother’s Age Birth Weight (g) Mother’s Age Birth Weight (g) 15 2289 19 3327 17 3393 17 2970 18 3271 16 2535 15 2648 18 3138 16 2897 19 3573 Make a residual plot of the data. Is it reasonable to assume a linear relationship between mother’s age and birth weight?

Activity – Launching Marbles What is the correlation between the angle of the launch ramp and the distance a marble travels? Work with your table to measure the distance a marble will roll when launched down a ramp propped against an increasing number of Stats books. Launch your marble using stacks of 1 to 6 books (6 data points). Measure the distance in inches. Write your data as an ordered pair on the board (# of books, distance in inches)

Activity – Launching Marbles 1) Enter the number of books in L1 and the distance in L2. 2) Make a scatterplot and comment on it (don’t need to copy it) 3) Calculate the correlation coefficient r and the LSRL. 4) Make a plot of the residuals (do need to copy this). 5) Do you think a linear model is suitable for the correlation between number of books and distance? Why or why not? 6) Using the LSRL estimate the distance a marble would roll with 7 books. Do you think this is a good estimate? Why or why not?