Chapter 13- Basic Sampling Issues

Question 1

Sampling

Answer 1

process of obtaining information from a subset (sample) of a larger group (population)

Question 2

sample vs. census

Answer 2

sampling is a collection of data from a sample.

Census is a collection of data obtained from or about EVERY member of the population of interest

Question 3

sample vs. population

Answer 3

sample- subset of all the members of a population of interest

population-entire group of people about whom information is needed

Question 4

7 step sampling process

Answer 4

1. define the population of interest
2. choose a data-collection method
3. identify a sampling frame
4. select a sampling method
   (e. g. probability samples- samples in which every element of the population has a known, nonzero likelihood of selection more$$. Or Nonprobability samples-samples in which specific elements from the population have been selected in a nonrandom manner.
5. determine sample size
6. develop operational procedures for selecting sample elements
7. execute the operational sampling plan

Question 5

simple random sample

Answer 5

the purest form of probability sampling. probability sample selected by assigning a number to every element of the population and then using a table of random number to select specific elements for inclusion in the sample.

probability of selection=sample size/population size

Question 6

Stratified samples

Answer 6

probability sample that is forced to be more representative through simple random sampling of mutually exclusive and exhaustive subsets.

steps

1. the original, or parent, population is divided into two or more mutually exclusive and exhaustive subsets (e.g. male and female)
2. simple random samples of elements from the two or more subsets are chosen independent of each other

Question 7

convenience

Answer 7

non probability samples based, on using people who are easily accessible (e.g. Frito-Lay uses their own employees for preliminary tests of new products)

Question 8

judgment

Answer 8

non probability samples in which the selection criteria are based on the researchers judgment about representativeness of the population under study

Question 9

snowball

Answer 9

non probability samples in which additional respondents selected based on referrals from initial respondents.
main advantage is reduction in search cost