Chapter 15 Count-based designs

15.1 Readings and Resources

• Kim, A. (2019) “Poisson Distribution — Intuition, Examples, and Derivation”
• Coxe, West, and Aiken (2009) “The Analysis of Count Data: A Gentle Introduction to Poisson Regression and Its Alternatives”

(Coxe, West, & Aiken, 2009)

(James et al., 2015)

James, E. L., Bonsall, M. B., Hoppitt, L., Tunbridge, E. M., Geddes, J. R., Milton, A. L., & Holmes, E. A. (2015). Computer game play reduces intrusive memories of experimental trauma via reconsolidation-update mechanisms. Psychological Science, 26, 1201-1215. Obtained from journals.sagepub.com/doi/abs/10.1177/0956797615583071

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• Download the SPSS data set (wide format)

• Download the Excel/R data set (wide format)

15.2 Visualizations

Interpreting Generalized Linear Models

## Contrasts set to contr.sum for the following variables: Condition_five, id

## Fitting 2 (g)lmer() models:
## [..]

## Mixed Model Anova Table (Type 2 tests, LRT-method)
## 
## Model: Intrusions ~ Condition_five + (1 | id)
## Data: .
## Df full model(s): 6
##           Effect df     Chisq p.value
## 1 Condition_five  4 23.51 ***   <.001
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '+' 0.1 ' ' 1

## emmeans are based on full model which includes all effects.

##                      Before No task Reactivation+Tetris  Tetris Reactivation
## Before              [1.100]  0.0407              0.0498  0.7388       0.0922
## No task             -0.3937 [1.493]              0.0006  0.8289       0.9997
## Reactivation+Tetris  0.5329  0.9266             [0.567]  0.0210       0.0012
## Tetris              -0.1867  0.2070             -0.7196 [1.286]       0.9119
## Reactivation        -0.3562  0.0375             -0.8891 -0.1696      [1.456]
## 
## Row and column labels: Condition_five
## Upper triangle: P values   adjust = "tukey"
## Diagonal: [Estimates] (emmean) 
## Lower triangle: Comparisons (estimate)   earlier vs. later

15.3 Model checking

15.3.1 Pearson residual

## `stat_bindot()` using `bins = 30`. Pick better value with `binwidth`.

15.3.2 Deviance residual

## `stat_bindot()` using `bins = 30`. Pick better value with `binwidth`.

References

Coxe, S., West, S. G., & Aiken, L. S. (2009). The analysis of count data: A gentle introduction to poisson regression and its alternatives. Journal of Personality Assessment, 91(2), 121–136. Retrieved from https://doi.org/10.1080/00223890802634175

James, E. L., Bonsall, M. B., Hoppitt, L., Tunbridge, E. M., Geddes, J. R., Milton, A. L., & Holmes, E. A. (2015). Computer game play reduces intrusive memories of experimental trauma via reconsolidation-update mechanisms. Psychological Science, 26(8), 1201–1215. Retrieved from https://journals.sagepub.com/doi/abs/10.1177/0956797615583071

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