Defining and assessing immediacy in single‐case experimental designs

R et al. looked at how we decide if a behavior changes right away in a single-case study.

They reviewed every way experts define “immediacy” and built a simple tool.

The tool is a randomization test that tries many start points and rules, then tells you which one shows the clearest jump.

No single rule for immediacy fits every graph.

Running many quick random tests and picking the most sensitive one gives a fair answer without eyeball bias.

Carlin et al. (2022) and Costello et al. (2022) also push for numbers instead of just looking. They like Tau and RD for overall effect, while R et al. give a way to spot the exact jump point.

Dowdy et al. (2021) say meta-analyses need clean indices; the new immediacy test can feed such reviews with a standard score.

McNellis et al. (2025) play with immediacy in real life by adding a snack delay. Their applied tweak shows why timing matters, backing the need for a sharp stat definition.

Next time you run an AB design, let the randomization test pick the clearest split instead of arguing with your team about where the line looks steep. You save time, reviewers trust the graph, and replications start from the same yardstick.