1. Describe the primary sampling units (PSU) and secondary sampling units (SSU) used in country C and in Kinshasa province in the study by Burnett et al.

Primary Sampling Unit:

Country C: Cluster from enumeration areas

Kinshasa Province: Neighborhoods with estimated target population

Secondary Sampling Unit

Country C: Household

Kinshasa Province Household

2. The Kinshasa province survey described in Burnett et al. had 3 sampling stages, what was the third sampling stage (hint: look under “Survey Objectives and Sample Size”?)

The third sampling stage in the Kinshasa province survey was health facility.

3. Based on the definitions of probability sampling and sampling frame found in the 2015 Vaccination Coverage Survey Reference Manual (section 3.6, section 6.2 and annex A), what do you think of the sampling frames used in country C vs. the sampling frame used in the survey described by Burnett et al.? Describe potential limitations of the frames used and how they may relate to sampling bias

Country C:

Sampling frame used: Recent enumeration area from 2016 population and health survey which is recommended by the manual.

Potential limitations: The quality of the mapping preparation of health survey.

Possible sampling bias: Little risk of sampling bias because each enumeration area has the same chance to be selected.

Kinshasa Province:

Sampling frame used: Sampling frame at each stage does not come from National statistics office as recommended

Potential limitations: Quality of EPI data. Quality of Polio microplan in 2013-2014. Each household does not have the same chance to be selected.

Possible sampling bias: Big risk of sampling bias: Boundaries of each neighborhood is not well defined. Movement of people between 2014 and the year of the survey is not considered.

4. In the Kinshasa province survey described in Burnett et al., the expected sample size was not reached. The authors describe two potential factors that may have contributed to this. How could have this been prevented? What are the main consequences of not reaching the expected sample size?

Per the author, the first factor is the use of DHS line list and the second is the lower response rate.

The two factor could be prevented during designing survey protocol.

For the first factor, use DHS HH list is not appropriate because DHS is more likely related to maternal health that’s why list is just for adult female. As a solution, It would be better to complete list of household by other list from administrative unit, election list or include in the survey protocol a mapping (denombrement et cartographie before survey.

For the second factor, this could be prevented by considering response rate as a parameter in the sample size calculation.

The main consequences of not reaching the expected sample size are reduction of precision (less precision with less sample).