Self-Assessment Questions (SAQs) for Study Session 15

Now that you have completed this study session, you can assess how well you have achieved its Learning Outcomes by answering the following questions. Some of the questions address Learning Outcomes from Study Session 14 as well as those from Study Session 15. Write your answers in your Study Diary and discuss them with your Tutor at the next Study Support Meeting. You can check your answers with the Notes on the Self-Assessment Questions at the end of this Module.

SAQ 15.1 (tests Learning Outcomes 15.1, 15.2 and 15.3)

Look again at Case Study 14.3 in the previous study session and then answer the following questions:

  • a.What is meant by the word ‘sampling’?
  • b.Describe what type of sampling method you will use to select your study subjects for the research described in Case Study 14.3.


  • a.Sampling is the process of selecting a number of study subjects from a defined study population.
  • b.Simple random sampling or systematic random sampling methods could be used to select mothers and children for the research outlines in Case Study 14.3.

Now read Case Study 15.4, and then answer the questions that follow it.

Case Study 15.4  Sofia is concerned about the rise in low birthweight babies

Sofia is a Health Extension Worker serving in a village where there are approximately 400 mothers who have given birth in the past five years. She suspects that the number of low birthweight babies is increasing and she would like to know more about the physical and socioeconomic conditions of the mothers to see if corrective actions should be taken. The Health Post records at present are not complete enough to draw conclusions and she does not have enough time or resources to interview every mother in the kebele. But she would like to study the problem, so she decides to take a sample of mothers to investigate.

SAQ 15.2 (tests Learning Outcomes 15.1, 15.2 and 15.3)

  • a.What does Sofia need to consider before she starts her research project?
  • b.What list does she need to have before she can select her sample?


  • a.Sofia needs to consider how many mothers she will investigate (the sample size) and what questions she will ask them.
  • b.Before she can select her sample, she needs a list of all the mothers in the kebele. This list is her sampling frame from which she can take her sample.

SAQ 15.3 (tests Learning Outcomes 15.1, 15.2 and 15.3)

  • a.What type of sampling method and what sample size is appropriate for the study Sofia wants to conduct in Case Study 15.4?
  • b.Using your knowledge from Study Session 14, what type of study design should Sofia use?


  • a.The appropriate sampling method is stratified random sampling, because she would like to know more about the physical and socioeconomic conditions of the mothers who have given birth in the past five years. The appropriate sample size would be close to 200 mothers from the total population of 400.
  • b.She could use a cross-sectional study design based on a random stratified sample, because she has neither the time nor the resources to interview all 400 recent mothers.

SAQ 15.4 (tests Learning Outcomes 15.1, 15.2 and 15.3)

Imagine you want to find out about contraceptive use by unmarried girls aged under 18 years in your kebele. However, you do not have an accurate listing of all the girls in this age group and you suspect that very few are using contraception.

  • a.How might you obtain a large enough sample of girls who are using contraception?
  • b.What ethical considerations would need to be taken into account in a study of this subject?


  • a.You would try to identify one or two girls in this age-group who are using contraception and ask them if they would agree to be interviewed by you, and if they know of any other girls in a similar situation who can be referred to you. Then you would ask the girls they referred to you if they know about anyone else who could be interviewed for your study, and so on. Using this snowball sampling method could build up a large enough sample to generate useful results about contraceptive use among young unmarried women.
  • b.You would have to ensure absolute confidentiality about who you interviewed and what they reported to you about such a sensitive subject as contraception among unmarried girls.

Summary of Study Session 15