Warm-upwith Multiple Choice Practice on 3.1 to 3.3

A scatterplot demonstrates the positive correlationbetween the number of churches and the number liquorstores in a growing town over the years.

1)The correlation appears to be a strong. Explain why eventhough there appears to be a strong correlation, why thetwo variables are not related.

2) Another scatterplot demonstrates a strong correlationbetween the number of people wearing shorts and thenumber of people eating ice cream on different days at thebeach. What is the lurking variable?

Answers to Statistics H.W. 3.2 P#3 and 5, E # 9 and 11

P3. As the school year progresses the student’s eraser weighs less (getssmaller). The eraser originally was 91.5 g (y-intercept) and it decreases at arate of about 1 gram/80 days (slope).P5. a) The explanatory variable is the student/faculty ration. The responsevariable is the % of alumni giving.b. Two points on the line are (10, 35) and (15, 25). These are not data pointsbut points on the line itself.

c. The y-intercept has no use because there would not be a situation where the student to faculty ratio would be zero.

d. The predicted giving rate would be 23% for a 16 faculty/student ratio. There will be a large error because the values are not clustered closely to the line.

e. Actual - Predicted = 9 - 8 = 1 for university with highest faculty/student ratio Actual – Predicted = 56 – 39 = 17 for university with highest giving rate

f. Actual – Predicted = 32 – 44 = - 8 g. The prediction error would be positive.

ratiofacultytostudent5

rategiving%10

Statistics Answers continued E #9 and 11

E 9. a. I. – E, II. – C, III – A, IV – D, V – B

b. I – A, II – E, III – B, IV – D, V - C

E 11. a. The slope is about 2.5 inches a yearb. The height of boys tend to be 2.5 inches/ year

from ages 2 to 14.c. Depending on the point plugged in, if age 3

was plugged in the resulting equation would be height = 2.5(years) + 31.5

D. A y-intercept of 31.5 would mean that the median height of a newborn is 31.5 inches.

Student of the day!Block 4

Student of the day!Block 5

Student of the day!Block 6

A.P. Statistics directions for Quiz• Answer every problem in complete sentences; The most

expensive house is …• Answer on a separate sheet of paper, you can staple it to your

quiz paper.• For 2e, I want to see how you calculate the residual. • For 2 g. create a table showing fat, calories (actual), predicted

and residuals, then show the sum of the residuals is zero.• When you finish, flip over your quiz and paper (make sure both

have your name) in front of you and work on the 3.1 to 3.3 Multiple Choice Practice.

• Work silently until I let you know everyone is done with their quiz.

• Once everyone is done with the quiz you, and your table can discuss the 3.1 to 3.3 Multiple Choice.

Statistics Extra Practice with linear regression

1) Does a person’s muscle mass decrease with age? Explanatory Var.

Response Var. 2) Using your graph paper, plot these on a

scatterplot and identify the point that represents age 71 and muscle mass is 82.

Muscle Mass Age

82 7191 64100 4368 6787 5673 7378 6880 5665 7684 65116 4576 5897 45100 53105 4977 78

Practice Using Muscle Mass vs. Age Data to find linear regression step-by-step

Muscle Mass Age

82 7191 64

100 4368 6787 5673 7378 6880 5665 7684 65116 4576 5897 45

100 53105 4977 78

Sum: ____ ______ ______ ______ _______ ____Mean: ___ ______

xx ))(( yyxx 2)( xx yy

Statistics Directions

• We will be finishing the rest of the Linear Regression worksheet after the quiz next class.

• Now you will complete the multiple choice portion of the worksheet.

• Complete what you can silently by yourself for the first 10 minutes.

• Then work with your table mates to select the right answers.

• Put your final right answers on a piece of paper to turn in for a participation grade.

• You can use your notes, textbook and ask me questions.

Computer Printout

Computing r2 from Printout

SSTotal

gressionSS

SSTotal

SSErrorSSTr

Re2

Multiple Choice Practice on 3.1 to 3.3

• Submit a sheet of paper with your table’s agreed upon answers for a participation grade.

• This will be graded for accuracy.• You may ask me questions.

Check to see if your vocabulary/formula list is completeQuiz is Tuesday 10/25 for A.P. Stats and Thursday 10/27 for Stats

3.1 – scatterplot, bivariate, linearity, clusters, outliers, trend, strength, generalization

3.2 – slope, y-intercept, predictor (explanatory variable), predicted (response variable), residual, interpolation, extrapolation, prediction error, least squares regression line (regression line), sum of squared errors (SSE)

3.3 – correlation, regression toward the mean, line of means, regression effect, regression toward the mean

Know formulas for: 1) slope in LSRL, 2) LSRL equation 3)SSE, 4) r (correlation coefficient), 5) r2 (coefficient of

determination) 6) slope from the correlation and SDs

Answers to Multiple Choice

1)d2)c3)a4)c5)c6)b7)c8)b9)e

H.W. Assignments

A.P. Statistics – 3.3 E #27, 34, 37, and 38Bring graph paper for activity next class.____________________________________________Statistics – 3.3 E # 27 and 34Be prepared for Quiz on 3.1 to 3.3.Bring calculator notes.