Re-Expression con’t

Chapter 10 Day 3AP Statistics

Warm UpTime elapsed(hours)

Concentration (Units/cc)

1 422 283 194 135 96 67 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 6420 6220 5930 11430 11830 10540 15340 17140 16550 23150 20350 23860 31760 32160 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 25191955 27551960 30201965 33341970 36911975 40661980 44301985 48251990 52551995 56622000 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