Basic Statistics

186 REGRESSION AND CORRELATION

(b) Contrast what you can learn from a scatter plot and T with what you can

12.4 The following table contains data from 17 countries. These countries are a

systematic sample from twice this number of countries that had a population

> 30 million people in 1998 and had complete data. The data were taken from

the US. Bureau of the Census, Statistical Abstracts of the United States; 1998,

118th ed., Washington, DC. It consists of the crude birth rate (CBR) or the

total number of births divided by the total population in 1998, life expectancy

(LifeExp) from birth in years for the overall population, and gross domestic

product (GDP) per capita for 1995. The GDP has been adjusted and then

converted to U.S. dollars.

learn from a confidence limit about the differences in the means.

Country CBR LifeExp GDP

Argentina

Brazil

Canada

Colombia

France

India

Iran

Japan

Mexico

Pakistan

Poland

S. Africa

Tanzania

Thailand

United Kingdom

United States

Egypt

20.0 74.5

20.9 64.4

12.1 79.2

24.9 70.1

27.3 62.1

11.7 78.5

25.9 62.9

31.4 68.3

10.3 80.0

25.5 71.6

34.4 59.1

9.8 72.8

26.4 55.7

40.8 46.4

16.8 69.0

12.0 17.2

14.4 76.1

7,909

4,080

19,000

2,107

746

26,290

348

2,449

41,160

2,521

482

5,404

3,185

134

2,806

19,020

27,550

State which model the data in the table follows.

Plot the scatter diagram when X = life expectancy and Y = crude birth

rate and fit a regression line.

Does the data appear to follow a straight line?

If life expectancy increased by 10 years, what do you expect to happen to

the crude birth rate?

Test that Ho : ,a = 0. If you test that p = 0, will you get the same P value?

12.5 Plot a scatter diagram using GDP per capita as the X variable and life expectancy
as the Y variable from the table in Problem 12.4.
(a) Fit a straight line to the plot of X = GDP and Y = LifeExp. Describe how

(b) Compute T.

the straight line fits the data.