Before building instruments, the data manager must decide what type of REDCap project is appropriate for the study. REDCap can support simple databases, surveys, longitudinal projects, registries, quality improvement tools, and hybrid models that combine staff-entered forms with participant-facing surveys. The structure chosen at the beginning affects how records, instruments, events, and exports are organized.
A classic REDCap project is the simplest structure. It contains one or more instruments, and each record represents one participant, facility, specimen, household, or other unit of observation. Classic projects are useful for cross-sectional studies, facility assessments, laboratory inventories, and small operational databases where data are collected once or where repeated timepoints are not central to the design. They are also useful for training because learners can
focus on instruments, fields, validation, and reports before moving into more complex longitudinal structures.
Survey projects allow data to be entered directly by respondents through survey links. These may be used for participant questionnaires, staff surveys, patient satisfaction tools,follow-up forms, or community assessments. In survey projects, the data manager must pay special attention to survey invitations, participant privacy, consent language, skip patterns, mobile usability, and whether respondents can save and return later. Surveys can reduce transcription because participants enter their own responses, but they also introduce risks related to comprehension, identity verification, and incomplete submissions.
Longitudinal projects are designed for studies in which the same participant or unit is assessed repeatedly across defined timepoints. A clinical trial with screening, enrollment, day7, day 28, and day 90 visits is a typical example. REDCap longitudinal projects use events to represent timepoints, and instruments can be assigned to one or more events. This structure is powerful because it avoids creating separate variables for each timepoint when repeated measurements follow a predictable schedule.
Hybrid projects combine database entry and survey functionality. A study coordinator may enter screening and enrollment data, while participants complete follow-up surveys through a link. Hybrid designs are common in pragmatic studies and implementation research, but they require careful planning so that participant-facing forms do not expose confidential data or allow unintended record access.
The choice of project type should follow the protocol, not personal preference. The data manager should consider the unit of observation, whether data are collected once or repeatedly, whether participants complete any forms themselves, whether the number of repeated observations is fixed or variable, and whether multiple sites require separate access. Choosing the wrong structure early can make the database difficult to maintain and may require major redesign later.