Self-Assessment Questions (SAQs) for Study Session 12

Now that you have completed this study session, you can assess how well you have achieved its Learning Outcomes by answering the following questions. 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 12.1 (tests Learning Outcomes 12.1 and 12.3)

Explain what is meant by bias in the collection of data, and why it should be avoided.


Bias is a distortion of information during data collection. Biased data collection does not show the true situation that you are trying to investigate so should be avoided if possible.

SAQ 12.2 (tests Learning Outcomes 12.1 and 12.4)

In a survey of ten households, the numbers of children in each family were found to be:

3, 1, 6, 4, 0, 3, 3, 5, 8, 4.

  • a.What is the mean number of children per household?
  • b.What is the median number?
  • c.What is the modal number?
  • d.What proportion of households has more than three children?
  • e.What percentage of households has more than four children?


  • a.The mean number of children per household is 3.7. To calculate the mean you add up all the numbers of children, which comes to 37, and divide by the number of households, which is 10.

  • b.The median number is 3.5. To calculate the median you rearrange the data in order: 0, 1, 3, 3, 3, 4, 4, 5, 6, 8. In this case, because there are an even number of records, there is no middle number so you have to take a mean of the two middle numbers, which are 3 and 4.

  • c.The modal number is 3. This occurs three times whereas other numbers occur no more than twice.

  • d.The proportion of families with more than three children is 5 out of 10. You could simplify this to say half the families have more than three children.

  • e.Three families have more than four children so the percentage is 3 divided by 10, multiplied by 100, which equals 30%.

Now read Case Study 12.1 and then answer the questions that follow it.

Case Study 12.1 Nutritional problems of women and children

You suspect that a large proportion of women and children in your kebele are malnourished, in particular women of childbearing age. You would like to determine the extent of this problem, and whether women perceive it as a problem. Furthermore you would like to know whether the women themselves could contribute to improving their nutritional status and how they might do this.

SAQ 12.3 (tests Learning Outcome 12.2)

What data collection methods might be appropriate to collect data for this investigation?


The data required is qualitative because it includes the women’s perceptions and opinions. Interviews and focus group discussions with women could be used to collect this data. Written questionnaires can also be used however this will only be suitable if all of the women are literate.

SAQ 12.4 (tests Learning Outcome 12.3)

Describe some biases that could occur during collection of data on nutritional problems of women and children in a situation like the one described in Case Study 12.1. How could these biases be avoided?


If data are collected using interviews, then the questions would need to be well prepared and devised so they did not lead to particular answers. All interviewers would need to receive appropriate training to ensure that they record the answers in the same way. Bias could also occur if respondents are prompted when answering questions. Respondents should not be handpicked, but selected according to consistent criteria.

SAQ 12.5 (tests Learning Outcome 12.4)

What sort of checks should be done on the data which has been collected before it is analysed and interpreted?


It is important to check data for consistency and missing values. You should check for errors in order to ensure that the data are reliable before you start to analyse and interpret the data.

SAQ 12.6 (tests Learning Outcome 12.5)

What ethical issues might you encounter while collecting data on the nutritional problems of women and children in Case Study 12.1?


It would be important to establish a relationship with, and to obtain informed consent from, each mother before you start to ask a lot of questions. You would have to be aware that nutritional status might be a sensitive issue.

Summary of Study Session 12