Today

  • What this module is about
  • How the module fits together
  • What the assessment asks you to produce
  • What the assessment criteria reward
  • What a good analysis report contains
  • How to choose a workable dataset and question

Module Team

Jens Roeser

Jens Roeser

Associate Professor in Psycholinguistics

Weeks 1-3: RMarkdown, linear models, model comparison.

Research: language processing and Bayesian modelling.

Thom Baguley

Thom Baguley

Professor of Experimental Psychology

Weeks 4, 5, 7: binary and count outcome models.

Author of Serious Stats (Baguley, 2012).

Nik Pautz

Nik Pautz

Lecturer in Cognitive Psychology

Weeks 8-10: multilevel models and revision.

Research: person perception, mixed-effects models, signal detection.

Module Aim

This module is about using advanced regression models to answer research questions with data.

The practical goal is that you can produce reproducible analysis reports that show:

  • why a model is appropriate
  • how the model was fitted
  • what the model estimates mean
  • how well the model answers the research question

Module Overview

The module builds from linear regression towards more flexible regression models.

We use one broad modelling framework to understand:

  • linear models for continuous outcomes
  • logistic regression for binary outcomes
  • count models for frequency outcomes
  • multilevel models for grouped or repeated data
  • one method that goes beyond the taught content

Assessment

Four short analysis reports, each using a dataset of your own choice:

  1. Binary logistic regression
  2. Count model: Poisson, negative binomial, or zero-inflated
  3. Multilevel regression model
  4. A method beyond the class content

Each analysis should be no more than 4 pages (excluding references).

Deadline: Friday 4 December 2026, 2 pm via Dropbox.

You will need to work on these reports throughout the term, not just at the end.

Psychological Relevance

Address some non-trivial question of some psychological relevance using your chosen data.

Psychology covers a wide range of topics and sub-fields, many of which overlap with other disciplines.

Consider the dataset described here, published in:

Bertrand, M., & Mullainathan, S. (2004). Are Emily and Greg more employable than Lakisha and Jamal? A field experiment on labor market discrimination. American Economic Review, 94, 991-1013.

The article was published in an economics journal, but it addresses implicit racial bias and is clearly related to psychology.

Assessment Requirements

For each analysis, you should:

  • state the research question and its psychological relevance
  • describe the dataset, source, key variables, and sample size
  • include useful descriptive statistics and visualisation
  • describe the statistical model formally
  • report fitted model results, including parameter estimates
  • report model predictions
  • compare plausible alternative models
  • assess quality of the model

Formative Assessment

The formative assessment is one short linear-regression report.

Deadline: Friday 23 October 2026, 2 pm.

This assessment is supported during the workshops. Across the first three weeks, you will have time to work on:

  • choosing a dataset and question
  • understanding the structure of a reproducible report
  • fitting and interpreting a model
  • showing predictions
  • comparing plausible models

Outcome Types

Outcome Example Possible model
Continuous reaction time, weight linear model
Binary correct/incorrect, yes/no logistic regression
Count number of errors count model
Continuous + repeated/grouped reaction times across trials within people multilevel model

Inspect the Formative Example

From the NOW learning room, open formative-assessment-example.pdf.

Do not worry about how the report was created yet. For now, identify:

  • where the research question is stated
  • where the data are described
  • where the table and figure are created
  • where the model is presented
  • where predictions are plotted
  • where model comparison appears
  • what parts you would need to replace for your own report

How Good Is This Example?

This is a good example of report structure, not a perfect report.

It is deliberately fairly simple so that we can see the main parts clearly. A marker might say that it could be stronger by adding:

  • clearer motivation from psychological theory or previous research
  • a more developed justification for the chosen predictors
  • a richer model comparison linked more directly to hypotheses
  • more detailed interpretation of the size and practical meaning of effects
  • a stronger discussion of limitations and what the model cannot show

For a first-class report, the structure needs to be combined with more independent thinking and a more convincing argument.

A Good Analysis Report

A clear analysis report usually contains:

  1. Research question
  2. Dataset description
  3. Descriptive statistics and plot
  4. Model description
  5. Model results
  6. Predictions
  7. Model comparison
  8. Short conclusion

Rest of This Session

The rest of the session, and your homework, is dedicated to identifying a topic and dataset for the formative assessment.

There are two steps:

  1. identify a topic and possible research question
  2. search for and evaluate a dataset that could answer that question

We will do Step 1 first, discuss ideas as a group, then move to Step 2.

Step 1: Start With Your Topic

Finding a dataset is easier if you start with an area you already care about.

A good starting point is your project lab topic, or a topic from another psychology module.

Write down:

  • one broad topic, such as sleep, anxiety, attention, memory, language, wellbeing, or ageing
  • one behaviour, judgement, score, or response that could be measured
  • one factor that might explain differences in that outcome

Exercise 1: Topic and Question (10 mins)

From the NOW learning room, open part-1-dataset-planning.html and use Exercise 1 as a guide.

Work in small groups and help each other. Do not search for datasets yet.

Keep in mind that the topic should connect to psychology, but do not worry about writing a full justification at this stage.

Answer the following questions (for yourself):

  • one broad topic area
  • one possible outcome
  • whether that outcome could be continuous
  • two or three possible predictors
  • one possible research question

Group Feedback

Each group should be ready to share one idea.

When listening to other groups, ask:

  • Is the topic psychologically relevant?
  • Is the possible outcome clear?
  • Could the outcome be continuous?
  • Do the predictors make sense for the question?
  • Can the question be made simpler?

Step 2: What Are You Looking For?

For the formative assessment, look for a dataset that can support a clear regression question.

A useful dataset usually has:

  • a psychological or behavioural topic
  • one outcome variable you can explain
  • at least one meaningful predictor
  • enough observations for a simple model
  • documentation that explains the variables
  • a file format you can open in R, such as CSV, Excel, SPSS, or R data

What Does a Continuous Outcome Look Like?

A continuous variable is numeric and has meaningful distances between values.

Good linear-model outcomes

  • reaction time in milliseconds
  • questionnaire total score
  • sleep duration in hours
  • age in years
  • accuracy proportion across many trials

Not continuous outcomes

  • sex, condition, group, diagnosis
  • correct/incorrect on one trial
  • yes/no response
  • number of errors or symptoms
  • participant ID

What Should the Dataset Look Like?

For a simple linear model, look for a rectangular table.

id age sex smoker reaction time (ms)
1 84 male former 701.7
2 37 female no 470.7
3 62 female yes 638.7
4 85 female former 708.0
5 73 male former 607.3

In this example, one row is one participant. The continuous outcome could be reaction time. Predictors could include age, sex, or smoking status.

First question for any dataset: what does one row represent?

Interactive Check (4 mins)

Here is a different dataset structure.

participant trial script lexicality correct reaction time (ms)
P001 1 pinyin word 1 1420
P001 2 chinese nonword 0 2955
P001 3 chinese word 1 817
P001 4 pinyin word 1 1571
P001 5 chinese nonword 1 1036

Identify:

  • the unit of observation
  • the variable that could be the continuous outcome
  • two variables that could be predictors
  • one variable that should not be treated as the outcome
  • one possible research question

Places to Search

Search Strategy

Search in two steps.

First, search for the topic and data source:

  • sleep questionnaire open data
  • memory reaction time dataset OSF
  • anxiety wellbeing csv codebook
  • attention experiment trial-level data

Then check whether the dataset has a usable outcome and predictors.

Do not choose a dataset just because the topic sounds interesting.

Using AI Tools for Dataset Search

Kaggle

Kaggle is popular with students and can be useful, especially for CSV files with previews and column metadata.

Treat it as a starting point, not automatic approval.

A Kaggle dataset is only suitable if you can:

  • identify the original source or documentation
  • understand the column names and values
  • find a usable outcome and predictors
  • explain a psychological or behavioural research question
  • check that reuse is allowed

Dataset Suitability Checklist

Before choosing a dataset, check:

  • file format is usable
  • variables are documented
  • one outcome variable is clearly identifiable
  • predictors are meaningful and not too numerous
  • there are enough observations for the planned model
  • cleaning needs are manageable within the assessment
  • reuse is allowed and ethically appropriate

Exercise 2: Search and Locate a Dataset (20 mins)

Use your topic from Exercise 1 and the part-1-dataset-planning.html document to save notes.

By the end, identify:

  • three search terms
  • one online source you checked
  • one candidate dataset
  • where the documentation or codebook is
  • one possible continuous outcome variable
  • possible predictor variables
  • whether the data could be analysed with a normal linear model
  • one risk or difficulty with the dataset

Dataset Search Debrief and Support

For each candidate dataset, check:

  • Does the research question match the data?
  • Is the outcome variable clear and continuous?
  • Could the outcome be analysed with a normal linear model?
  • Is the source documented well enough?
  • What would make the analysis simpler?

Use the remaining time to get help with these checks or to find a better dataset.

Before Next Workshop

Software setup

If needed:

  1. Install R from CRAN: https://cran.r-project.org/
  2. Install RStudio Desktop Open Source: https://posit.co/downloads/
  3. Open RStudio and run:
install.packages("tidyverse")
library(tidyverse)

Bring next time

Check that:

  • R and RStudio open successfully
  • library(tidyverse) runs without an error
  • you have one candidate dataset or are ready to use the class data
  • you are ready to create a new RStudio project

Recommended Reading

References

Andrews, M. (2021). Doing data science in R: An introduction for Social Scientists. SAGE Publications Ltd.

Baguley, T. (2012). Serious stats: A guide to advanced statistics for the behavioral sciences. Macmillan International Higher Education.

Gelman, A., Hill, J., & Vehtari, A. (2020). Regression and other stories. Cambridge University Press.