11 LMM: Overall Strategy

11.1 Research objective

  • Define your primary and secondary research objectives

  • State your research hypothesis

  • Described the overall purpose of the model

11.2 Data

  • State the complete experimental design

  • State the data collection protocol

  • Identify different sources of variations

11.3 EDA: Summary & Plot

  • Exploratory data analysis: Summary statistics

  • Exploratory data analysis: Plots

  • Exploratory data analysis in line with the research hypotheses

11.4 Model specification

  • Specify the modelling scenarios

  • Identify the fixed and random effects structure

  • Write down the model equations

  • Identify model selection strategies: fixed and random effects

11.5 Model fitting: SPSS

  • Conduct model fit

  • Conduct model selection

11.6 Final Model

  • Identify the final model

11.7 Model diagnostics

  • State all model assumptions

  • Check all model assumptions

11.8 Model evaluation

  • Evaluate the model in line with the research hypothesis

  • Summary Estimates: Random effects

  • Summary Estimates: Fixed effects

  • Explore magnitude, direction and precision of effect size

  • Comparison of means between treatment groups

  • Prediction: Predicted values with and without random effects

11.9 Report results

  • Report the results

  • Interpret the results

  • Draw appropriate conclusions