TOPIC 10

TOPIC 10 - RANDOM SAMPLING

(a) No; those with more passionate views of Elvis are more likely to pay to voice their opinions.

(b) One flaw is that those with telephones or vehicles in 1936 tended to be the more affluent segment of society. Another flaw is that those who took the time to respond probably tended to be less satisfied with the incumbent.

(c) Elvis: population - all American adults, sample - those radio listeners who chose to pay to call in station
Literary Digest: population - all American adults, sample - those who received the questionnaire and chose to respond

10-2: Sampling Students

(a)

Sample	# in favor	Prop. in favor
1	6	.4
2	7	.47
3	8	.53
4	8	.53
5	7	.47

(b) The proportion of students in favor changed from sample to sample.

Mean of proportions = .48

Range of proportions = .53-.40 = .13

(c) The shape of the distribution of proportions is symmetric bell-shaped. The average value is .6 and the proportion values range between .33 to .87.

10-3: Sampling Students (cont.)

(b) When you sample from only the first three floors, the distribution of sample proportions is (1) symmetric, mound-shaped, (2) has an average of .4, (4) ranges from .2 to .6.

(d) The average sample proportion value is .4 which is significantly less than the population proportion of .6.

10-4: Sampling U.S. Senators

(a) Gender: categorical (binary)
Party: categorical (binary)
State: categorical
Years of service: measurement

(b) - (e) These answers vary from student to student.

(f) no; no; almost certainly no

(g) No, the random sampling method is not biased because it does not systematically under- or over-represent certain groups.

(h) You would have to use three-digit labels for the representatives, read off three digits at a time from the table, and ignore numbers from 436 to 999 and 000.

(i)

p = .93
= 8.72

10-10: Parameters and statistics

(a) parameter - p
     statistic -
     statistic -
    parameter -

(b) statistic -
     parameter - p
    parameter M
    statistic - s