Boxcar function
Definition: The boxcar function is a function which has values 0 everywhere except for specific time window(s) where its value is a constant. With respect to experimental studies, the boxcar function serves as a representation of time periods during which specific events occur (e.g., a stimulus or a nuisance factor). The function typically takes a rectangular form with a value of 1 when the event is ‘on’ with a width equal to the duration of the stimulus and 0 when the event is ‘off’. In data analysis (e.g., General Linear Model), the boxcar function is used to model the experimental design or any other relevant binary (on/off) regressor or factor. In these use-cases, a value of 0 usually corresponds to the absence of the factor (e.g., no stimulation or “off” state, i.e., interstimulus interval), and a value of 1 corresponds to the presence of the factor (e.g., stimulus presentation or “on” state, i.e., stimulus block).
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References: https://doi.org/10.1016/B978-012372560-8/50003-6https://doi.org/10.1016/B978-012372560-8/50014-0
https://doi.org/10.1006/nimg.1998.0351
Related terms: regressor, general linear model, block design, design matrix