# Large Coverage Errors for Interviewers Bias

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1) A poll is planned to determine what proportion of all students favor an increase in fees to support a new track and field stadium. A questionnaire will be published and the first 1000 completed questionnaires will be analyzed. Which of the following errors will be associated with the sample?

A.

Only non-sampling errors

B.

Sampling errors and errors due to selection bias

C.

Sampling errors only

D.

Errors due to interviewer bias and selection bias

2) A sufficiently large coverage error will result in which of the following?

A.

Statistics about the actual population rather than the target population

B.

Non-response bias

C.

Inability to perform inferential statistics

D.

Probability sampling

3) A statistician working for the Department of the Interior is constructing a systematic random sample of trees in a forest preserve. All trees have been identified and numbered with a non-invasive number attached to the bark. The statistician wishes to estimate the mean height of the trees in the forest preserve, and has calculated an appropriate sample size of n=43 trees. The 587th of the 731 trees in the preserve was selected as the first observation in the sample. What is the tree number of the second observation in the sample?

A.

604

B.

544

C.

630

D.

588

4) Which of the following is an example of statistical inference?

A.

Calculating the mean age of patients discharged from hospitals in New York State in 1997.

B.

Counting the number of patients who file malpractice suits after being discharged from hospitals in New York State.

C.

Calculating the amount of fly spray needed for your orchard next season.

D.

Calculating the mean number of fruit trees damaged by Mediterranean fruit flies in California last year.

5) Which of the following statements is not true?

A.

Estimating parameters is an important aspect of descriptive statistics.

B.

Scientific progress consists of continual refinement of theories through hypothesis testing.

C.

A statistical test may be significant yet have no practical importance.

D.

Statistics is the science of collecting, organizing, analyzing, interpreting, and presenting data.

6) The collection and summarization of the socioeconomic and physical characteristics of the employees of a particular firm is an example of

A.

a parameter.

B.

a statistic.

C.

inferential statistics.

D.

descriptive statistics.

7) A supermarket has determined that daily demand for eggs has a bell-shaped distribution, with a mean of 55 cartons and a standard deviation of six cartons. If the supermarket begins each morning with a stock of 61 cartons of eggs, approximately what percentage of days will there be a surplus of eggs?

A.

?68%

B.

?84%

C.

?16%

D.

?18%

8) The average score for a class of 30 students was 75. The 20 male students in the class averaged 70. The 10 female students in the class averaged

A.

75

B.

70

C.

85

D.

80

9)

Textbook Price Number of Textbooks

$25 to $35 2

35 to 45 16

45 to 55 5

55 to 65 7

65 to 75 20

Estimate the standard deviation of the price of a textbook.

A.

196.78

B.

729.00

C.

14.03

D.

33.85

10) Ten bolts were selected randomly from a production line and the diameter of each was measured. Why do these diameters not have a binomial distribution?

A.

Diameter is a continuous random variable.

B.

They do have a binomial distribution.

C.

They have equal probability of success.

D.

The diameters of the bolts are not independent of one another.

11) Which of the following is a characteristic of every binomial distribution?

A.

Each outcome is mutually exclusive.

B.

The outcome of a trial depends on the number of trials.

C.

Each outcome is dependent on the previous outcome.

D.

The probability of success increases from trial to trial.

12) Which of the following cannot generate a Poisson distribution?

A.

The number of defects in a new automobile

B.

The number of goals in the World Cup soccer game

C.

The number of people at a movie theatre on Friday evening

D.

The number of customers arriving at an ATM in a minute

13) Past history shows that 70% of college students prefer Pepsi. Groups of nine students are selected. Describe the histogram that would represent this distribution. The histogram would be:

A.

left-skewed with nine columns.

B.

right-skewed with ten columns.

C.

left-skewed with ten columns.

D.

right-skewed with nine columns.

14)

The Big Red Arcade and Pizza Palace caters to young teens and sells tokens to play arcade games for 25¢ each and slices of pizza for 50¢ each. The distribution of sales of pizza slices per customer and sales of arcade tokens per customer is below.

# Slices of Pizza 0 1 2 3 4 5

Probability 0.05 0.10 0.20 0.30 0.15 0.20

# Arcade Games 0 1 2 3 4 5

Probability 0.01 0.04 0.15 0.20 0.25 0.35

What is the total expected per customer revenue for pizza slice sales and arcade token sales?

A.

$2.42

B.

$1.34

C.

$6.69

D.

$2.60

15)

The Big Red Arcade and Pizza Palace caters to young teens and sells tokens to play arcade games for 25¢ each and slices of pizza for 50¢ each. The distribution of sales of pizza slices per customer and sales of arcade tokens per customer is below.

# Slices of Pizza 0 1 2 3 4 5

Probability 0.05 0.10 0.20 0.30 0.15 0.20

# Arcade Games 0 1 2 3 4 5

Probability 0.01 0.04 0.15 0.20 0.25 0.35

What is the probability that revenues from pizza slice sales will be greater than $1.00 per customer?

A.

.85

B.

.43

C.

.95

D.

.65

16) The standard error of the sample mean is equal to 5 when n=25. If the sample size increases by a factor of four, how will the standard error change?

A.

It will be cut to ¼ of 5

B.

It will quadruple

C.

It will double

D.

It will be cut in half

17) A random variable follows the student's t distribution. The probability that it will be positive is

A.

less than 0.50.

B.

0

C.

1

D.

0.05

18) The use of the student's t distribution requires which of the following assumptions?

A.

The population is normal

B.

The population variance is known

C.

The sample is drawn from a positively skewed distribution

D.

The sample size is greater than 30

19)

A study of 200 insomniacs paid for by the Serta Mattress Company found that the average insomniac counted 350 sheep before falling asleep, with a standard deviation of 120. An insomniac is a person who has difficulty falling asleep. Some useful numbers might be:

=NORMSINV(0.89) 1.2265

=NORMSINV(0.945) 1.5982

=TINV(0.89,199) 0.1385

=TINV(0.11,199) 1.6053

=TINV(0.055,199) 1.9302

Out of the 200 insomniacs, 98 reported regularly watching The Late Show with David Letterman before they began to count sheep. Calculate the margin of error for a 78% confidence interval of the true proportion of insomniacs who regularly watch David Letterman before counting sheep.

A.

0.136

B.

0.056

C.

0.164

D.

0.043

20)

Construct a 95% confidence interval estimate for the difference between the means of two normally distributed populations, where the unknown population variances are assumed not to be equal. Summary statistics computed from two independent samples are as follows:

The upper confidence limit is:

A.

24.911.

B.

28.212.

C.

5.788.

D.

19.123.

21)

A study of 200 insomniacs paid for by the Serta Mattress Company found that the average insomniac counted 350 sheep before falling asleep, with a standard deviation of 120. An insomniac is a person who has difficulty falling asleep. Some useful numbers might be:

=NORMSINV(0.89) 1.2265

=NORMSINV(0.945) 1.5982

=TINV(0.89,199) 0.1385

=TINV(0.11,199) 1.6053

=TINV(0.055,199) 1.9302

Calculate an 89% confidence interval for the true mean number of sheep counted by insomniacs.

A.

350±13.62

B.

350±13.56

C.

350±16.38

D.

350±10.41

22) When no point lies outside the control limits of a chart, we conclude that variation in the process is

A.

due to common cause and there is enough evidence to infer that the process is out of control.

B.

due to special causes and there is enough evidence to infer that the process is under control.

C.

due to common cause and there is not enough evidence to infer that the process is out of control.

D.

due to special causes and there is not enough evidence to infer that the process is out of control.

23) When the results of a process are either defective or acceptable, the charts used for SPC are called

A.

control charts for attributes.

B.

control charts for variables.

C.

control charts for in control process.

D.

control charts for out of control process.

24) When a change has occurred in the mean of the process distribution, the result is referred to as

A.

a cycle.

B.

instability.

C.

a trend.

D.

a level shift.

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The large coverage errors for interviewers bias are examined.

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Please see the attached solution.

1) A poll is planned to determine what proportion of all students favor an increase in fees to support a new track and field stadium. A questionnaire will be published and the first 1000 completed questionnaires will be analyzed. Which of the following errors will be associated with the sample?

A.

Only non-sampling errors

B.

Sampling errors and errors due to selection bias

C.

Sampling errors only

D.

Errors due to interviewer bias and selection bias

Sampling error is inherent anytime you are considering a subset of the population. Selection bias is also an issue here since we are analyzing only the first 1000 completed questionnaires.

2) A sufficiently large coverage error will result in which of the following?

A.

Statistics about the actual population rather than ...

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