Section author: Laiton Hedley

Restructuring Data

What is Wide vs Long Format?

Within data analysis, two common data structures are wide format and long format.

In wide format, each row represents a participant and repeated measurements are stored in separate columns (one column per outcome at each time point or condition). For example, below are quiz scores for students during Weeks 2, 4, and 6 of a semester displayed in wide format:

Table 13 Wide Format Example

ID	ScoreWeek_2	ScoreWeek_4	ScoreWeek_6
1	30	50	70
2	20	30	55
3	40	50	52

Each row represents a unique student (ID), and their quiz scores at Weeks 2, 4, and 6 are stored in separate columns. To run a repeated measures ANOVA in jamovi, the data must be in wide format as shown above.

In long format, each row represents a single measurement occasion, giving multiple rows per participant. The same data in long format:

Table 14 Long Format Example

ID	Time	Score
1	Week_2	30
1	Week_4	50
1	Week_6	70
2	Week_2	20
2	Week_4	30
2	Week_6	55
3	Week_2	40
3	Week_4	50
3	Week_6	52

Long format makes it easy to summarise, plot, and model change over time because time is represented explicitly as data rather than being embedded in column names. It is also required for mixed modelling.

Restructuring with jReshape

Important

Restructuring data in jamovi requires the jReshape module, which is not installed by default. Install it by clicking the + icon in the top-right of jamovi and searching for jReshape.

Once installed, a Data option will appear under the Analyses tab, containing the jReshape options.

Wide to Long

1. Click the Analyses tab, select Data, then select Wide to Long.

2. Move the columns that represent repeated measurements (e.g. ScoreWeek_2, ScoreWeek_4, ScoreWeek_6) into the Columns to row box.

3. Under Target Variable, give the new column a meaningful name (e.g. Score).

4. Under Index Variable, name the variable that will identify the time point or condition (e.g. Time).

5. Check the data preview in the output window. If it looks correct, click Create and jamovi will open a new window with the restructured data.

Long to Wide

1. Click the Analyses tab, select Data, then select Long to Wide.

2. Move the outcome variable (e.g. Score) into the Rows to Columns box.

3. Move the variable identifying each time point or condition (e.g. Time) into the Indexing Variables box.

4. Move the participant identifier (e.g. ID) into the ID Variable box.

5. Check the data preview, then click Create.