The scenario describes an intervention implemented across multiple participants three sets of parents which immediately suggests a multiple baseline or multiple probe design The critical details are the concern about timeconsuming baseline data collection and the expectation that baseline data will be stable and at a low level no prior exposure to PECS A multiple probe design is specifically utilized in such situations where an extended continuous baseline is impractical or unnecessary It involves collecting intermittent probes of data during baseline instead of continuous daily data collection significantly reducing the resources and time required while still establishing experimental control by staggering the introduction of the intervention across participants A multiple baseline design would involve continuous baseline collection which the BCBA aims to avoid due to time constraints and dropout risk Reversal and Changing Criterion designs are generally not suitable for demonstrating control across multiple participants in this specific context