A synthetic repeated measures dataset suitable for testing longitudinal analysis functions. Contains realistic treatment effects, missing data patterns, and within-subject correlations.
Format
A data frame with 480 rows and 10 variables:
- subject_id
Subject identifier (factor, 1-120)
- group
Treatment group (Control, Treatment)
- age
Age in years (numeric)
- gender
Gender (Male, Female)
- time
Time point (T1, T2, T3, T4)
- time_numeric
Time point as numeric (1-4)
- outcome_score
Primary outcome measure (continuous)
- secondary_outcome
Secondary outcome measure (continuous)
- physio_measure
Physiological measure (continuous)
- questionnaire_score
Questionnaire rating (ordered factor, 1-7)
Source
Generated synthetically with realistic longitudinal correlation patterns and treatment effects. No real study data was used.
Details
Study design features:
120 subjects (60 per group)
4 measurement occasions
Balanced treatment assignment
Realistic dropout patterns (0% at T1, 35% by T4)
Treatment effect grows over time (interaction effect)
Autoregressive error structure
Effect size approximately Cohen's d = 0.6
Missing data patterns reflect realistic longitudinal study attrition with higher dropout in later time points. The treatment effect demonstrates a clear Group x Time interaction suitable for repeated measures testing.
See also
longitudinal_data_wide for the wide format version.
survey_data for the cross-sectional survey dataset.
Examples
# Load required packages and data
library(dplyr)
data(longitudinal_data)
# Repeated measurements are analysed in the wide format
# (see longitudinal_data_wide), e.g. with friedman_test()
# Descriptive statistics by group and time
longitudinal_data %>%
group_by(group, time) %>%
describe(outcome_score)
#>
#> Descriptive Statistics
#> ----------------------
#>
#> Group: group = Control, time = T1
#> ---------------------------------
#>
#> --------------------------------------------------------------------------
#> Variable Mean Median SD Range IQR Skewness N Missing
#> --------------------------------------------------------------------------
#> outcome_score 26.224 26.360 3.352 14.937 4.466 -0.387 60 0
#> --------------------------------------------------------------------------
#>
#> Group: group = Control, time = T2
#> ---------------------------------
#>
#> --------------------------------------------------------------------------
#> Variable Mean Median SD Range IQR Skewness N Missing
#> --------------------------------------------------------------------------
#> outcome_score 26.996 27.505 2.749 11.326 4.418 -0.508 51 9
#> --------------------------------------------------------------------------
#>
#> Group: group = Control, time = T3
#> ---------------------------------
#>
#> --------------------------------------------------------------------------
#> Variable Mean Median SD Range IQR Skewness N Missing
#> --------------------------------------------------------------------------
#> outcome_score 27.460 27.901 2.865 11.694 4.963 -0.081 49 11
#> --------------------------------------------------------------------------
#>
#> Group: group = Control, time = T4
#> ---------------------------------
#>
#> --------------------------------------------------------------------------
#> Variable Mean Median SD Range IQR Skewness N Missing
#> --------------------------------------------------------------------------
#> outcome_score 27.944 28.253 3.452 14.255 4.756 -0.334 41 19
#> --------------------------------------------------------------------------
#>
#> Group: group = Treatment, time = T1
#> -----------------------------------
#>
#> --------------------------------------------------------------------------
#> Variable Mean Median SD Range IQR Skewness N Missing
#> --------------------------------------------------------------------------
#> outcome_score 25.216 25.328 3.924 17.558 4.457 -0.098 59 1
#> --------------------------------------------------------------------------
#>
#> Group: group = Treatment, time = T2
#> -----------------------------------
#>
#> --------------------------------------------------------------------------
#> Variable Mean Median SD Range IQR Skewness N Missing
#> --------------------------------------------------------------------------
#> outcome_score 27.078 27.087 4.200 20.332 5.596 0.189 55 5
#> --------------------------------------------------------------------------
#>
#> Group: group = Treatment, time = T3
#> -----------------------------------
#>
#> --------------------------------------------------------------------------
#> Variable Mean Median SD Range IQR Skewness N Missing
#> --------------------------------------------------------------------------
#> outcome_score 29.288 29.515 3.619 15.305 5.903 0.211 48 12
#> --------------------------------------------------------------------------
#>
#> Group: group = Treatment, time = T4
#> -----------------------------------
#>
#> --------------------------------------------------------------------------
#> Variable Mean Median SD Range IQR Skewness N Missing
#> --------------------------------------------------------------------------
#> outcome_score 30.826 30.552 3.059 11.133 5.117 0.250 37 23
#> --------------------------------------------------------------------------