Figure 3. Adherence to Procedural Testing Steps, According to Instructions Provided and Reader Experience.

A, Adherence to procedural steps among 278 participants at the first self-testing visit. B, Adherence to procedural steps among 173 participants attending a second self-testing visit. Error bars indicate 95% CI for the proportion of participants who performed each step correctly, estimated according to a binomial distribution using the Wilson Score method.

^aStep deemed to be most important for a valid result according to literature or expert opinion.