1 q71

Determine the critical value of (CHI SQ) C2 with 1 degree of freedom in each of the following

circumstances:

a) a n df C2

0.01 16 1

b) a n df C2

0.025 11 1

c) a n df C2

0.05 8 1

2 q73

Fitting a straight line to a set of datayields the following prediction line:

Y_hat = 2 + 5Xi b0 b1

2 5

a) Interpret the meaning of the Y intercept, b0. X = 0

b) Interpret the meaning of the Y slope b1. Y = 0

c) Predict the meanvalue of Y for X = 3. X = 3

Y_hat =

3 q74 If SSR = 66 and SST = 88, compute the coefficient of determination, r^2, and interpret its meaning.

SSR 66 SST 88

r2 =

So, 0% of the variation in the dependent variable can be explained by the

variation in the independent variable.

4 q75 If SSR = 120 why is it impossible for SST to equal 110?

SSR 120 SST 110

5 q73+

Circulation is the lifeblood of the publishing business. The larger the sales of a magazine,

the more it can charge advertisers. Recently, a circulation gap has appeared between

the publishers’ reports of magazines’ newsstand sales and subsequent audits by the

Audit Bureau of Circulations. The data in the file circulation.xls represents the reported

and audited newsstand sales (in thousands) in 2001 for the following 10 magazines:

Magazine Reported (X) Audited (Y)

YM 621 299.6

CosmoGirl 359.7 207.7

Rosie 530 325

Playboy 492.1 336.3

Esquire 70.5 48.6

TeenPeople 567 400.3

More 125.5 91.2

Spin 50.6 39.1

Vogue 353.3 268.6

Elle 263.6 214.3

a) Construct a scatterplot of the data.

For these data b0 b1

b) Interpret the meaning of the slope, b1, in this problem.

c) Predict the mean audited newsstand sales for a magazine that reports

newsstand sales of $400. $400

The expert interprets meanings of intercepts. The mean values of the intercept is determined