Module 6: Sampling

Question 1

With regards to the bulls eye analogy what are the 4 rings and the 1 arrow?

Answer 1

Rings: outer to inner
1. Population
2. Target population
3. Accessible population 
4. Sample 
Arrow: 
1. One participant

Question 2

What can be described as selecting a group of people that will be used in a study to represent the entire population?

Answer 2

Sampling

Question 3

Differentiate between target and accessible populations:

Answer 3

The target population is the group of people the researcher would like to be able to generalize findings about while the accessible population are people who meet the criteria and are accessible to the researchers

Question 4

What can sampling representativeness be described as?

Answer 4

The ability of the sample’s key traits to very closely represent those of the population. This makes the findings generalizable

Question 5

Over or under representation of key variables can lead to ______ ______.

Answer 5

sampling bias

Question 6

In which type of sampling does every member of the population have a chance to being selected to be included in a study’s sample? Selection is random.

Answer 6

Probability sampling

Non-probability sampling uses non-random methods of

Question 7

Non-probability Sampling Strategies include: (5)

Answer 7

1. Convenience sampling
2. Snowball sampling
3. Quota sampling
4. Consecutive sampling
5. Purposive sampling

Question 8

What is considered the weakest sampling method?

Answer 8

Convenience sampling

Using just the population readily available may not yield results generalizable to the target population

Question 9

What is snowball sampling?

Answer 9

Also called network sampling. Sample members, or ‘seeds’, refer people who meet a study’s eligibility criteria

Question 10

What is quota sampling?

Answer 10

A method of sampling in which researchers identify population strata (sub-populations of the complete population) and determine how many participants from each stratum are needed.

Question 11

What is consecutive sampling?

Answer 11

Recruiting all of the people from an accessible population who meet the eligibility criteria over a specific time interval or for a specific sample size

Question 12

What type of sampling uses a researchers knowledge about a population to select participants for a study?

Answer 12

Purposive sampling

Question 13

4 types of probability sampling strategies include:

Answer 13

1. Simple random sampling
2. Stratified random sampling
3. Cluster sampling
4. Systematic sampling

Question 14

What is simple random sampling?

Answer 14

All people in a given population have some chance of being in the sample which is randomly selected

Question 15

What is stratified random sampling?

Answer 15

Subdividing the population into homogeneous subsets or strata and then selecting elements randomly.

Question 16

What type of probability sampling involves selecting large groupings (ex-nursing schools) first, typically with successive subsampling of smaller units (ex-nursing students) in a multistage approach?

Answer 16

Cluster sampling

Question 17

What is systematic sampling?

Answer 17

Method using selection of every k’th case from a list resulting in an essentially random sample

Question 18

What is the standard distance between sampled elements in systematic sampling called?

Answer 18

sampling interval

Question 19

Why should quantitative studies have larger sample sized than qualitative studies?

Answer 19

Results will be more likely to be representative of the population, decreasing statistical error

Question 20

What does the an effect size express?

Answer 20

The strength of relationships among research variables

Question 21

What is the method used to estimate sample size needs?

Answer 21

Power Analysis

Question 22

What are the 4 factors that affect the power of a study?

Answer 22

1. Significance criterion (alpha)
2. Population effect size (Y)
3. Sample size (N)
4. Power (1-beta)

Question 23

What is alpha representative of in a power analysis?

Answer 23

0.05= 5% chance that a Type I error will occur; that the outcome occurred by chance and not as a result of the independent variable

Question 24

What does the population effect size refer to in a power analysis?

Answer 24

The magnitude of the relationship between research variables. A statistical representation of the strength between 2 variables. This is often obtained from other similar studies conducted prior or by a pilot study

Question 25

What does the power component of power analysis refer to?

Answer 25

Probability of obtaining a significant result and not committing a Type II error.
1 (100%, power) - 0.2 (beta, chance of committing a type II error)= 80% (desired amount of power)

Question 26

What type of power analysis is conducted before a study begins?

Answer 26

A priori