Quantitative Research

To ensure the highest quality of social science research, YPC adheres to a 10-step research methodology. The application of the methodology is supervised by the experienced staff at the YPC headquarter in Sanaa.

1. Desk Review and Baseline Preparation
Before implementing fieldwork or designing the questionnaire, YPC researchers conduct thorough background research on all issues and subject areas concerning the research objective defined by the client.

2. Questionnaire Design
The collected background information, the objectives of the project, as well as the client's input serve as the basis for the questionnaire design. YPC's knowledge of local circumstances and use of language ensures the effectiveness of the research instrument and maximal research results.

3. Drawing the Sample
YPC chooses a large enough sample size, allowing meaningful analysis across different regions of the country and among different demographic groups. Marginalized groups, especially persons with disabilities, Yemeni youth, women, and urban and rural residents are all covered by the sample. If additional measures are deemed necessary to ensure sufficient interviews are conducted with any particular demographic group, further purposive sampling is employed.
for most of nationwide surveys YPC use the follwoing sampling methodology:
The sample will be drawn in a multi-stage, random probability proportional to population distribution. The sample universe will consist of all Yemeni governorates.
 In constructing the sample, YPC will draw on the 2015 estimates of the population, based on the 2004 national census conducted by the Central Statistical Organization. depending on the objective of the survey the respondents are ll respondentsthose who aged 18 or more (in some cases 15 or more). Fifty percent of respondents are female. YPC usually suggest drawing the rural and urban samples separately to guarantee representation. That is, setting a quota for number of urban to rural districts sampled to guarantee representation.

Selection of PSUs

Governorates form the first level of stratification. Thus, we distribute the requested sample size among Yemen’s 21 governorates- in proportion to their population size. Subsequently we identify the number of PSUs (primary sampling units) in each governorate by dividing the number of allocated interviews in each governorate by the required number of interviews in each PSU (generally 10).
For the purposes of staying consistent across all governorates, Hara (for urban areas) and village (for rural areas) are considered as the primary Sampling Units (PSUs).
The Yemen Polling Center has access to a population database that has estimates for all PSUs (as defined above) for all governorates. This excel file contains the following columns: Governorate name, District name, Sub-district name, Hara or village name (PSU) and the total population for every PSU.
 We then identify the “interval number by dividing the cumulative population of the governorate to the required number of PSUs that need to be selected in that governorate.
Interval number is the number that indicates the interval between every two randomly selected PSUs in the excel file. This number basically depend on the accumulative population column in the excel file that YPC has.

Selection of Starting Points

Starting points are selected by field supervisors in every PSU. During the supervisors’ training at YPC headquarters, supervisors are instructed how to select the right starting point within PSUs. Supervisors are instructed to select 1-3 starting points within every PSU.

Selection of Households

Once the starting point is identified by the supervisor,  he/she accompanies every interviewer (2 or 4 interviewers in the team) to the sampling starting point and identifies the first household where interviewing begins by using the right hand rule and an interval of 3 households (excluding the starting point), the interviewer will attempt a contact at the third household.  Every interviewer will visit different households without any overlap with his/her colleagues’ households since the supervisor himself identified the right households that should be visited for every interviewer. Supervisor gives instructions about the walk pattern that every interviewer should follow within PSU. In the specific illustration we can see the main households that every interviewer should visits as well as the two households for substitutions

 Every team consists of equal number of female and male interviewers (1 male and 1 female or 2 males and 2 females)
Due to cultural reasons, interviewers can interview only respondents of their gender. Once the household is chosen, the interviewer lists all adult 18+ members of a particular gender (male if the interviewer is male and female if the interviewer is female) and their ages using specific table.

4. Pretesting the Questionnaire
Once the questionnaire is completed, it is pretested in Sana’a and in additional key target areas. The pretest serves to identify any questions that are not easily understood by respondents, any difficulties the enumerators have in gathering the data with the survey instrument, and any additional issues or difficulties.

5. Data collection
For the data collection in the field, primary sampling units (PSUs) are randomly selected (PPS) within each governorate. Enumerators are given a walking and skip pattern to determine in which households the survey should be implemented in. In reporting response rates, YPC accords with all standards established by the World Association of Public Opinion Research and American Association for Public Opinion Research.

6. Quality Controls
All supervisors have long-standing experience in managing and supervising the teams of enumerators and administering the questionnaires in their respective governorates. The supervisor is responsible for managing and supervising the field work, reviewing the field questionnaires, contacting the enumerators on an hourly basis, and keeping the project officers at headquarters directly informed about the whereabouts of the enumerators at all times. The first completed surveys are checked by the YPC headquarters in terms of correct skip patterns, missing data, and legibility. At least 10 percent of the completed surveys are verified by telephone or visits.

7. Data Entry & Processing
All data is entered into SPSS and is available in ASCII or STATA format. The codes for any open-ended questions are developed after the pre-test. Categories for responses are created to encompass all possible answers. To ensure all data is entered correctly, ten percent of all the work returned from each member of YPC’s data entry team is independently verified.

8. Final Report Preparation
After completing the project, YPC prepares a final report which tailored to the needs of the clients, includes all important data.