Types of Studies
Not meant to be exhaustive.
Broad Classes
Quantitative and Qualitative
This is about what data is collected.
Quantitative focuses on the measurable (statistics involved of course).
Qualitative is about observation (description, explanation) that produces artifacts (e.g. interviews, photos, sketches of spaces, notes) and may use some quantitative data. It can be exploratory research (see and refine questions, understand opportunities.) Can be used for evaluation (why are informatics interventions used or not used?)
Prospective and Retrospective
This is about the temporality of the data that is collected.
What it says on the tin. Look forward or backward in time. One is cheaper because things have already happened. One gives you more control.
Observational and Experimental
This is about how the data is collected.
Measurement and Demonstration
Observational
No exposure assigned (i.e. no influence on subjects). Descriptive. Analytical: give associations through comparisons. Can infer cause-effect relationships. Less common in interventions research unless you’re studying existing technologies/interventions.
Cross-Sectional Studies
Slice in time. There is no temporality in cross-sectional studies. It’s a slice in time. Because of this, there cannot be causal assertions. You can only speak of associations.
Cohort Studies
Prospective: Study begins at point of exposure. You have a lot of control. You cannot always assume causality. Kinda costly for rare outcomes (gotta recruit a lot of people!)
Retrospective: Study begins at point of outcome. No control (lol). Inexpensive (already happened, someone else paid the bill). But you’re limited in terms of sampling and quality (already happened). And you cannot always assume causality.
Cohort studies can start with cross-sectional studies where you can establish prevalence.
Case-Control Studies
These can only be retrospective. You can study just one outcome. Big challenge is bias: you recruit your cases separately from controls (you can match, for example, to get over this problem). Doesn’t have the temporal ordering that cohort studies do.
This is why you need to match: cases are OK but controls are hard: you don’t want confounding by covariates or time.