Re-Expression con’t

Chapter 10 Day 3

AP Statistics

Warm UpTime elapsed(hours)

Concentration (Units/cc)

1 42

2 28

3 19

4 13

5 9

6 6

7 4

PenicillinAssimilation

a. Straighten these data using re-

expressionb. Use your model

to estimate the concentration of penicillin after 8

hours

More Practice

Problems!

BrakesSpeed(mph)

StoppingDistances (ft)

20 64

20 62

20 59

30 114

30 118

30 105

40 153

40 171

40 165

50 231

50 203

50 238

60 317

60 321

60 276

1. Explain why the linear model is not appropriate.

2. Re-express the data to straighten the scatterplot and give the re-expressed model.

3. Estimate stopping distance for a car traveling 55mph.

World PopulationYear Population

(millions)

1950 2519

1955 2755

1960 3020

1965 3334

1970 3691

1975 4066

1980 4430

1985 4825

1990 5255

1995 5662

2000 6057

a.Model (Scale the years)b.Use your model to

predict population for 2005.

What have we learned?

1. Recognize when a well-chosen re-expression may help you improve and simplify your analysis

2. Understand the value of re-expression to improve symmetry, to make scatter about the line more constant, and to make a plot more linear

3. Recognize that when a pattern indicates that no re-expression can improve the structure of the data

4. Know how to re-express you data and how to use the calculator

5. Be able to reverse any common re-expressions to put a predicted value or residual back into the original units

What have we learned?

6. Be able to describe a summary or display of a re-expressed variable making clear how it was re-expressed and giving its re-expressed units.

7. Be able to describe a regression model fit to re-expressed data in terms of the re-expressed variables

What have we learned?

ClassworkBook Page 243 # 29

Homework

Page 241 # 24, 28, 30