Consumer Survey Methodology for Small Islands: Sampling and Fieldwork Guide

Designing a statistically sound consumer survey for a market of 50,000 people is genuinely different from designing one for a market of 5 million. The finite population correction changes sample size requirements. The geographic coverage challenge shifts from stratification across regions to near-census coverage of a small island. The sampling frame is built from sources that do not exist as standard databases. And the data quality protocols must account for the social dynamics of small communities where interviewers and respondents often inhabit overlapping social networks. This guide covers the methodological decisions that matter most in Caribbean small island survey research.

Understanding the Finite Population Context

The statistical theory of survey sampling was developed primarily in the context of large populations where the number of potential respondents is so large relative to the sample that each interview adds negligible new information about the population distribution. This infinite population assumption does not hold for island markets with adult populations under 100,000, and it breaks down completely for markets under 20,000. Understanding this matters not just for sample size calculations but for the entire logic of how you achieve representative coverage.

In a large market, a random sample of 400 people from a population of 5 million gives you 0.008% of the population, and the statistical theory assures you this is enough to estimate population parameters within defined confidence bounds. In a market of 10,000 adults, a sample of 150 is 1.5% of the population, and achieving this genuinely random sample requires covering virtually every geographic subdivision of the island and recruiting across all demographic strata with a thoroughness that is logistically much more demanding than the pure statistical arithmetic suggests.

Building the Sampling Frame

The sampling frame is the list or map from which sample units are drawn. In Caribbean small island markets, there is no single ideal sampling frame: telephone directories are outdated, online panels do not exist at scale, and household registers are not publicly available in most markets. HRG uses a multi-source approach anchored in census enumeration district maps. These ED maps, produced by national statistical offices in conjunction with population and housing censuses, divide each island into numbered geographic units with population counts and physical boundary descriptions.

The area probability sampling approach derived from these maps works as follows. First, all EDs in the country are listed with their population counts. Second, EDs are selected with probability proportional to population size using systematic random selection. Third, within each selected ED, a local field supervisor walks the enumeration area and produces a household listing. Fourth, a fixed number of households is randomly selected from this listing using a random starting point and fixed interval. Fifth, within each selected household, an eligible adult is selected using the Kish grid or next-birthday method to ensure random respondent selection at household level.

Questionnaire Design for Island Populations

Questionnaire design for Caribbean small island face-to-face surveys must account for a literacy and educational attainment distribution that differs from metropolitan research contexts. Literacy rates vary from over 95% in Barbados and Trinidad to below 50% in parts of rural Haiti (World Bank literacy data, 2023). Even in high-literacy markets, respondents with primary school education as their highest qualification have difficulty with complex multi-attribute scales, conditional branching logic expressed in question text, and abstract concepts presented without concrete referencing.

HRG's questionnaire design standards for Caribbean small island surveys include: maximum scale length of 5 points for general consumer samples (7-point and 10-point scales can be used with higher-education segments); all product and brand names tested in cognitive pilot interviews to verify local recognition and pronunciation; skip patterns managed by the interviewer rather than built into question text; and response options presented on show cards for face-to-face interviews wherever the response set exceeds 3 items. Every questionnaire undergoes a cognitive pre-test with 10 to 15 members of the target population before main fieldwork begins, with a debrief designed to surface comprehension problems and culturally inappropriate phrasings.

Fieldwork Logistics and Data Quality

Logistics specific to island fieldwork include boat or ferry transportation for multi-island nations such as St. Kitts and Nevis, Antigua and Barbuda, or Trinidad and Tobago. Field supervisors in these markets must factor in ferry schedules and weather conditions that can cancel sailings when planning geographic coverage. HRG builds at least 2 extra travel days into any multi-island fieldwork plan as contingency for ferry or inter-island flight disruption. For very small outer islands with infrequent transport connections, we schedule fieldwork to align with regular ferry days and complete all interviews in a single visit to avoid repeat travel costs.