Questions

1.a. How many strata does the Harmonia survey will have?

Ans 1.a. 10 strata as each province will form one strata.

1.b List and briefly describe at least two advantages and disadvantages of having these many strata compared to having more, for example 100 (one for each district)? (MANDATORY)

Ans 1.b.

Advantages:

• Resource effective: Budget, time and manpower.
• Quality control: Easier to supervise a survey in 10 strata than in 100 different strata.

Disadvantages:

• District level stratified information may not be available.
• Will not be able to specify barriers to better coverage at the decentralized level.

2. How much will the sample size decrease or increase (overall) if you were to design a survey with and with +/-8% precision per strata or +/- 3% precision per strata (as opposed to +/-5% precision per strata used now). Just provide the ‘Total Completed Interviews Needed’. Think about the importance that the desired precision has on overall sample size. (OPTIONAL)

• +/-5% precision per strata: 10,481
• +/-8% precision per strata: 4,645
• +/-3% precision per strata: 26,282

3.a What kind of data do you need to collect to complete a table like the one below? (MANDATORY)

Ans 3.a. The kind of data needed is as follows:

• For the sampling frame: Census data with month and year.
• Facility based records: Children of age of interest.
• From the field work:

1. Recall from the caretaker / mother
2. Home based records
3. Field work record of the number of houses interviewed, responded, refused, unoccupied, etc.

3.b How does this table relate to potential selection bias and what cautions should you have when interpreting the vaccination indicators if response rate is not 100% and/or several households could not be interviewed? (MANDATORY)

Ans 3.b.

Potential selection bias:

• If a non-probability sampling is followed then different households may have unequal and unquantified probabilities of being selected as the starting point.
• If fieldworkers interview easily accessible households and ignore difficult to access households as vaccination uptake between these two cases may differ.
• If the sampling frame is not reliable then there will be a difference in the characteristics of the included and excluded population and this will skew the findings.

Cautions to be taken if interpreting vaccination indicators if the response rate is not 100% and/or several households could not be included:

• Questions and confirm the quality of the field implementation of the survey before analysis of the survey data.
• Is there a difference in the characteristics (Socio-demographic, access, etc.) for the areas where we have more non-responders or from the area where most of the households could not be covered.
• If required, prepare an interim reports with action points to strategize the further coverage in these areas.

4.a What variables do you need to collect or define in the analysis to estimate a [weighted] vaccination coverage with the first dose of diphtheria-tetanus-pertussis containing vaccine (DTP1) and with the third dose of diphtheria-tetanus-pertussis containing vaccine (DTP3) among children aged 12-23 months in each stratum by:

a) ‘documented evidence of vaccination (home-based record – HBR OR facility-based record – FBR)’:

• Stratum ID
• Age of the child and /or Date of birth of the child
• Sex of the child
• Tick on DTP1 and / or Date of DTP1
• Tick on DTP3 and /or Date of DTP3

b) ‘by recall’:

• Stratum ID:
• Age of the child and / or Date of birth of the child
• Sex of the child
• Caretaker’s recall if the child received an injection on the outer thigh to prevent him from getting Whooping cough, diphtheria and tetanus (and/or HiB and Hepatitis B).
• How many times the child received this injection.

c) ‘by documented evidence of vaccination + recall’.

• Stratum ID:
• Age of the child and / or Date of birth of the child
• Sex of the child
• Asking the caretaker to show the vaccination card and/or asking the caretaker where and how many times the child received the vaccination in the survey period of interest.

[Do NOT include the data you need to calculate weights]. (MANDATORY)

4.b How does this table relate to potential information bias and what cautions should you have when interpreting the vaccination indicators in surveys with “low” percentage of documented evidence?

(MANDATORY)

Ans 4.b.

Potential information bias:

• Caretaker may feel obliged to say that the child was vaccinated if the interviewer does not keep a neutral outlook (Social desirability bias).
• Caretaker may not remember the site of the injections.
• Caretaker may not remember how many times the injection was given.
• Caretaker may not have been present when the injection was given and the alternate caretaker may not be available for interview.

Cautions in interpretation:

• Plan for handling missing data in analysis.
• Plan to triangulate some data with the Facility based records.
• If an unexpected trend is visualized, then further exploration before giving out inference.