1. STUDY POPULATION SAMPLE/INCLUSION AND EXCLUSION CRITERIA
Presenters
Anne Obondo/Dennis Donovan

2. Objectives
We expect that at the end of this presentation, you will be able to:
Define your population sample
State your inclusion and exclusion criteria.

3. Population Generally:
Population denotes the number of people within a given boundary

4. In research,
Target population
Refers the entire group of subjects or participants you wish to generalize the study findings
For example,
All institutionalized alcoholics
Or all university students
Or Slum dwellers who abuse alcohol

5. Accessible population
Is the subset of the target population and is also known as the study population.
May be limited to region, state, city, county, or institution
For example,
All institutionalized alcoholics in Nairobi county
Or all university students in Nairobi county

6. Sample and sample frame
Is a subset of the population and a typical representative of the larger group or population.
Sample frame
Is a list of all the participants in the population from which the sample is drawn

7. For example,
For example, if you study is “assessment of the effectiveness of counseling services in Nairobi”
You need a list of all counselling clinics from which you will draw your study sample
In opinion polls – electoral register and telephone directory.
Gives the participants equal opportunity of being selected as subjects or participants

8. Effective sample frame
Has information about participants.
Is organized in a logical and systematic fashion
Include every participant of the population
No elements from outside the population of interest are present
The data is 'up-to-date‘
( Tunner A. G.,2012)

9. Illustrative Diagram – Population sample

10. Relationship between population and sample
Population is the entire group
Sample is a subset of the population.
Before sampling it is important to carefully and correctly define the population
Sample is used to make generalizations about a population

11. Sample must be good size to warrant statistical analysis
The more diverse the population the larger the sample.
Sample is drawn from the population and the population takes conclusions from the results obtained from the sample.

12. Research triad

13. Why sample your population
Makes study population easily accessible since it is impossible to study the whole population.
Generalization of the findings to the target population can be adequately made.
Makes it easy for statistical data analysis
However, in qualitative studies you may not need to sample your population

14. Examples
Psychiatric morbidity among adult HIV/AIDS patients attending a comprehensive care centre at a city council clinic in Nairobi.
Target population
Study population

15. Problems in study population sample
Bias in
Selection
Sources of bias
Omitting people in hard to reach groups
Replacing selected individuals with others, because they are in accessible
Use of outdated list as sample frame

16. When population sample is not characteristic of the population.
Some members of the population are not included in the frame
The non-members of the population are included in the frame. (Leslie Kish, 1995).
Being too ambitious

17. Some points to consider
Consider whether your study is quantitative or qualitative.
Define your population from which the sample is to be drawn.
Consider sample frame with a appropriate contact information
Will the population that you want to study meet your objectives

18. Is my study population accessible?
Is my study population representative of the target population?
Is it diverse that I can make inferences.

19. Inclusion and Exclusion Criteria
Inclusion criteria are characteristics that the prospective subjects must have if they are to be included in the study.
Exclusion criteria are those characteristics that disqualify prospective subjects from inclusion in the study.

20. Inclusion and exclusion criteria may include factors such as age, gender, race, ethnicity, type and stage of disease, the subject’s previous treatment history, and the presence or absence (as in the case of the “healthy” or “control” subject) of other medical, psychosocial, or emotional conditions.
Defining inclusion and exclusion criteria increases the likelihood of producing reliable and reproducible results, minimizes the likelihood of harm to the subjects, and guards against exploitation of vulnerable persons

21. General Population of Interest
Inclusion Criteria
Exclusion Criteria
Sample

22. SMART-ED Inclusion Criteria
18 years old or older
Seeking medical treatment at the ED
Had adequate English language proficiency
Were capable of providing informed consent
Had a score of 3 or greater on the 10-item Drug Abuse Screening Test (DAST-10)
Reported at least 1 day of drug use in the 30 days prior to screening
Were willing to participate in the protocol
Had access to a telephone.

23. SMART-ED Exclusion Criteria
Prisoners or in police custody
Currently engaged in or actively seeking addiction treatment
Resided more than 50 miles from the follow-up location
Were unable to provide sufficient contact information
Had already participated in the study.

24. Screening and Randomization
4,005 participants endorsed past-30d drug use (27% of TADs).
Of these, 1,285 were randomized (32% of drug users).
Probably most of those not randomized were excluded because they did not meet DAST ≥ 3 criterion.

26. Pre-Screened: Screened: Randomized: 1285 (427 BIB, 427 SAR, 431 MSO) 3-mo f/u: mo f/u: mo f/u:  analysis: 1139

27. References
Turner, Anthony G. "Sampling frames and master samples“. United Nations Secretariat, 12/11/2012. 
Leslie Kish (1995). Survey sampling. Wiley. ISBN Retrieved 11 January 2011. [