prepdat: Preparing Experimental Data for Statistical Analysis

Prepares data collected in an experimental design for statistical analysis (e.g., analysis of variance ;ANOVA) by taking the individual data files and preparing one table that contains several possibilities for dependent variables. Most suitable when measuring reaction-times and/or accuracy, or any other variable in an interval or ratio scale. Functions included: file_merge(), read_data() and prep(). The file_merge() function vertically merges individual data files (in a long format) in which each line is a single trial within the experiment to one single dataset. The read_data() function reads a file in a txt or csv format that contains a single dataset in a long format table and creates a data frame from it. The prep() function aggregates the single dataset according to any combination of between and within grouping variables (i.e., between-subjects and within-subjects independent variables, respectively), and returns a data frame with a number of dependent measures for further analysis for each experimental cell according to the combination of provided grouping variables. Dependent measures for each experimental cell include among others means before and after rejecting all values according to a flexible standard deviation criterion/s, number of rejected values according to the flexible standard deviation criterion/s, proportions of rejected values according to the flexible standard deviation criterion/s, number of values before rejection, means after rejecting values according to procedures described in Van Selst & Jolicoeur (1994) (suitable when measuring reaction-times), standard deviations, medians, means according to any percentile (e.g., 0.05, 0.25, 0.75, 0.95) and harmonic means. The data frame prep() returns can also be exported as a txt file to be used for statistical analysis in other statistical programs.

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