Choosing The Study Subjects: Specification, Sampling, And Recruitment

Question 1

Target Population

Answer 1

The large set of people throughout the world to which the results will be generalized

Question 2

Accessible population

Answer 2

Is a geographically and temporally defined subset of the target population that is available for study

Question 3

Study sample

Answer 3

Is the subset of the accessible population that participates in the study

Question 4

Inclusion criteria

Answer 4

Define the main characteristics of the target population that pertain to the research question

Question 5

Demographic characteristics for a study

Answer 5

Race
Age
Economic background

Question 6

Clinical characteristics

Answer 6

Health status

Marital status

Question 7

Geographic characteristics in a study

Answer 7

Where are the participants in the study from?

Question 8

Temporal characteristics

Answer 8

Between what dates will the participants be gathered?

Question 9

Exclusion criteria

Answer 9

Indicates subsets of individuals who would be suitable for the research question were it not for characteristics that might interfere with the success of follow-up efforts, the quality of the data, or acceptability of randomized treatment

Question 10

Convenience sample

Answer 10

Study sample of people who meet the entry criteria and are easily accessible to the investigator

Question 11

Systematic sample

Answer 11

Resembles simple random sampling in first enumerating the population but differs in that the sample is selected by a preordained periodic process (e.g. Taking every other person from a list of town residents)

Question 12

Stratified random sample

Answer 12

Involves dividing the population into subgroups according to characteristics such as sex or race and taking a random sample from each of these strata

Question 13

Cluster sample

Answer 13

Is a random sample of natural groupings (clusters) of individuals in the population. Cluster sampling is very useful when the population is widely dispersed and it is impractical to list and sample from all its elements. A disadvantage is the fact that naturally occurring groups are often homogeneous for the variable of interest

Question 14

What is an important method to achieve a representative sample?

Answer 14

Minimize the number of nonrespondants

Question 15

How do you avoid falling short with the recruitment goals?

Answer 15

Estimate the magnitude of the recruitment problem empirically with a pretest

Plan the study with an accessible population that is larger than believed necessary

Make contingency plans should the need arise for additional participants