Chapter 7

Question 1

Sampling error

Answer 1

The difference between the value of a sample statistic and the value of the corresponding population parameter.
Can’t be avoided.

Question 2

Non-sampling error

Answer 2

Errors occurring in collecting, recording and tabulation of data.
Can be minimized.

Question 3

Probability distribution of X bar

Answer 3

Sampling distribution

Question 4

Sample mean is a…

Answer 4

Random variable

Question 5

Mean of x bar is always equal to…

Answer 5

The mean of the population

Question 6

Unbiased estimator

Answer 6

When the mean of a sample statistic is equal to the value of the corresponding population parameter

Question 7

The standard deviation of x bar is…

Answer 7

Not equal to the standard deviation of the population.
SD of x bar decreases as n increases.
SD of x bar is less than population SD.

Question 8

Finite population correction factor

Answer 8

Multiplied to the SD sample when n/N is less than or equal to 0.05.

Question 9

Sampling distribution shape of x bar: case one

Answer 9

If the population from which the samples are drawn are normally distributed, then the sampling distribution of the sample mean, x bar, will also be normally distributed.

Question 10

Sampling distribution shape of x bar: case two

Answer 10

If the populations from which the samples are drawn is not normally distributed, according to the central limit theorem, for a large sample size (n greater than or equal to 30) the sampling distribution of x bar is approx. Normal, irrespective of the shape of the population distribution.

Question 11

Empirical rule

Answer 11

68.26 % of the sample means will be within one standard deviation of the population mean.
95.44% is within 2 SD’s.
99.74% is within 3 SD’s.

Question 12

Population proportion

Answer 12

Represents the fraction of individuals in a population that possess a certain characteristic.
P =x/ N
X= number of elements in the population that possess the characteristic.
N = total elements in population

Question 13

Sample proportion

Answer 13

Estimates the population proportion based on a sample taken from the population.
Phat = x/n
X= number of elements in the sample that possess a specific characteristic.
N= total sample elements

Question 14

Sampling error for proportions

Answer 14

P hat - p
Difference between sample proportions and population proportion.

Question 15

Sampling distribution of p hat

Answer 15

Since p hat is a Radom variable it has a probability distribution

Question 16

Mean of the sample proportion is equal to…

Answer 16

The population proportion

Question 17

Sampling distribution shape of p hat

Answer 17

According to the central limit theorem, the sample distribution of p hat is approx. normal if np >5 and nq >5