Unit IV - In-Class Activities

17-1: Penny Spinning

(a) Answers vary.

(b) statistic; 

(c) no

(d) no

17-2: Critical Values

(a)

(b) .975

(c) 1.96

(d) z* = 1.44

17-3: Penny Spinning ( cont. )

(a) Answers vary.

(b) no

(c) - (d) Answers vary.

(e) look at 

(f) Simple random sampling, large sample size

17-4: Penny Spinning (cont.)

(a) - (b) Answers vary.

(c) no

(d) 95% of all intervals generated by this procedure do capture the actual parameter value.

17-5: Effect of Confidence Level

(a) (Asks for prediction)

(b)-(c) Answers vary , but the intervals should get gradually wider (with the same center).

(d) Requiring less confidence allows for a narrower interval.

17-6: Effect of Sample Size

(a) (Asks for prediction)

(b)

(c) The intervals get narrower as the sample size gets larger.

(d) twice as big

(e) cuts the half-width in half

18-1: American Moral Decline ( cont. )

(a) (.7294, .7906)

(b) simple random sample; large sample size

(c) .0306

(d) This margin of error comes from the half-width of the 95% confidence interval.

(e)

• False
• False
• True
• False

(f) (Asks for prediction)

(g) .0187; .0419

(h) The margin-of-error decreases as the sample size increases.

(i) Greater, since the sample size of men only would be smaller than that of the complete sample.

18-2: Congressional Term Limits

(a) need 601 people (rounded up from 600.25)

(b) (Asks for prediction)

(c) 9604

(d) (Asks for prediction)

(e) 16,590

(f) not at all

(g)

(h) the whole population of American adults

18-3: Female Senators ( cont. )

(a) (.034, .146)

(b) no

(c) horribly biased sampling method

(d) No, because we know the whole population of the 1994 U.S. Senate.

18-4: Students' Credit

(a) - (b) Answers vary.

(c) It is doubtful that the results would generalize to a larger population.

19-1: ESP Testing ( cont. )

(a) .25

(b) no

(c) yes

(d) yes

(e) Wilma

(f) normal distribution with mean .25 and standard deviation .0433

(g) no

(h) yes

(i)

19-2: ESP Testing ( cont. )

(a) :  = .25
(The subject is just guessing and would get 25% right in long run.)

(b) :  .25
(The subject does better then guessing and would get more than 25% right in long run.)

(c) z = 1.39

(d) p-value = .0823

(e) If Barney were just guessing, he'd do this well or better about 8.23% of the time in the long run.

(f) There is some, but not much, evidence to support the claim that Barney does better than just guessing.

(g) yes; yes; no

(h) no; no; no

(i)

19-3: Effect of Sampling Size

(a) parameter, since it pertains to the entire population of adult Americans.

(b) :  = .5; :  .5

(c) statistic

(d) sample size

(e) (Asks for prediction)

(f)

(g) if the sample size was quite large

20-1: Penny Spinning ( cont. )

(a) , the proportion of all penny spins that would land heads

(b) two-sided;
you are looking at "euqally likely" without regard to more or less.

(c) :  = 0.5; :  ­ 0.5

(d) z = -1.633; p-value = .1025

(e) z = 1.633; p-value = .1025

(f) no

(g) :  = 0.5; :  < 0.5

(h) z = -1.633; p-value = .0512

(i) z = 1.633; p-value = .9488

(j) The sample result is not even in the direction of the alternative hypothesis.

(k)

20-2: American Moral Decline ( cont. )

(a) (.729, .790)

(b) no

(c) - (g)

(h) Whenever the confidence interval includes the value, the test is not significant. Whenever the confidence interval does not include the value, the test is significant.

20-3: Advertising Strategies

(a) z = 1.556; p-value = .0598

(b) z = 1.697; p-value = .0448

(c) z = 3.394 ; p-value = .0003

(d) a and b

(e) b and c

20-4: Tax Return Errors ( cont. )

(a)  = .30626

(b) (Asks for prediction)

(c) : =.3 ; :  not equal to.3
z = 3.055; p-value = .0023

(d) (.301, .312)

(e) no

(f) no

20-5: Elvis and Alf ( cont. )

(a) z = 216.887
p-value = 0 (virtually)

(b) (.569, 571)

(c) The sampling procedure was horribly biased in favor of Landon.