Intro lecture 5

Question 1

Why would you use a probability sample?

Answer 1

• Probability samples are most likely to produce a sample that
truly represents the population.
• They are purely mathematical or mechanical
• Allow calculation of probability of outcomes with great precision

Question 2

Define sampling ratio

Answer 2

the ratio of the sample size to the size of the target

population

Question 3

What is Sampling distribution and how is it visualized

Answer 3

the distribution of a sample statistic among many
repeated random samples

• Visualized in a plot of many random samples

Question 4

What is a simple random sample?

Answer 4

sample elements selected from
the frame based on a mathematically random selection
procedure

Question 5

What is Systematic Sampling

Answer 5

An approximation to random
sampling in which you select from a list of sample elements,
each #th element

Question 6

What is stratified sampling?

Answer 6

a random sample is drawn from

multiple sampling frames, each for a part of the population

Question 7

What is Cluster (multi-stage) sampling

Answer 7

Clusters are randomly sampled, then a random sample of elements is taken from the sampled clusters.

• Take a random selection of cities, then in each city sample persons

Question 8

Why use stratified sampling and how to do it? 2 steps

Answer 8

• Population exists of pre-defined groups
• We want to be sure that all groups are represented in the sample
• Step 1: divide the population into strata
• Step 2: Draw simple random or systematic sample from each subpopulation

Question 9

Noem de 6 non-probability samples

Answer 9

1. Convenience Sampling
2. Quota sample
3. Purposive sampling
4. Snowball (network) sampling
5. Deviant Case samplint
6. Sequential sampling

Question 10

Explain what Convenience sampling is

Answer 10

a non- random sample in which you use an non-systematic selection method that often produces samples very unlike the population.

Question 11

Explain what Quota sampling is

Answer 11

non-random sample in which you use any
means to fill pre-set categories that are characteristics of the population.

• E.g. mall sample: aim for 50% male and 50% female

Question 12

Difference Quota sampling and stratified sampling?

Answer 12

idk

Question 13

Explain what Purposive sampling is

Answer 13

a non-random sample in which you use many diverse means to select units that fit very specific characteristics.

• Qualitative research: find experts, people with experience

Question 14

Explain what Snowball Sampling is

Answer 14

a non-random sample in which selection is based on connections in a pre-existing network.

• E.g. homeless, heroin users