Chapter 10

Question 1

What are advantages of using survey methods

Answer 1

1. Standardization
2. Ease of administration
3. Ability to tap the “unseen”
4. Suitability to tabulation and statistical analysis
5. Sensitivity to subgroup differences

Question 2

What is sample accuracy?

Answer 2

How close a random sample’s statistic is to the true population’s value it represents

Larger a sample is, less sample error

Question 3

What are the two types of error in sampling?

Answer 3

Nonsampling error: pertains to all sources of error other
than sample selection method and sample size

Sampling error: involves sample selection and sample size
Margin of sample error = 1.96 x √(P*Q/N)

Question 4

What is variability?

Answer 4

How similar or dissimilar responses are to a given question

Question 5

What is a confidence interval?

Answer 5

The confidence interval is a range and the endpoints
define a certain percentage of the responses to a
question.

• Based on the normal distribution
• We can use the normal distribution because of the
  central limit theorem
• The confidence interval =/p + − margin of sampling error

Question 6

How to estimate variability?

Answer 6

How to estimate variability
– Use data from a previous study on the target population.
– Conduct a pilot study of the target population.
– Assume worst case maximum variability (p and q = 50%)
– Estimate standard deviation by dividing range by 6

Question 7

What to do when sampling from small populations?

Answer 7

Use the finite population multiplier to determine small size.
Small Population Sample Size = Sample Size Formula * √(N-n)/(N-1)
n= sample size
N = population

Question 8

What are important factors to consider about sampling?

Answer 8

• Sampling method (not sample size) is related to
  representativeness
• Only a probability sample (random sample) is truly
  representative of a population
• Selection method not sample size determines sample
  representativeness
• Sample size determines accuracy of findings