I am having some trouble understanding the difference (if any) between a Within Subject and a Repeated Measure design.

A few resources online seem to suggest that they are often interchangeable or almost the same. Note the below descriptions

Within Subject Design

In a within subject design, unlike a between subjects design, every single participant is subjected to every single treatment, including the control.

From: https://explorable.com/within-subject-design

Repeated Measures Design


The term 'repeated measures design' is often interchanged with the term 'within subjects design,' although many researchers only class a subtype of the within subjects design, known as a crossover study, as a repeated measures design.

What is a Repeated Studies Design?

The repeated measures design uses the same subjects with every condition of the research, including the control.

From: https://explorable.com/repeated-measures-design

From what I understand, and please someone help me here, all Repeated Measure Designs are Within Subject Designs but not all Within Subject Designs are Repeated Measure Designs?

If the above is correct, in what circumstances are they different?

Could anybody give me some pointers here?

Any help is as always, hugely appreciated


It is ironic that even on this site when I tried to find the "within-subject" tag it recommended I use the "repeated-measures" tag :-)


1 Answer 1


They are both one and the same. Repeated Measures IMHO is a more general term that is also applied to longitudinal studies or designs in which data are collected over the same subject across time, say if you were measuring the weight gain of animal from a given diet across time. From the links you posted, it appears that they think crossover designs are more popularly called repeated measures, but again I think it is more important to account for any lack of independence within the data by whatever name you call it :) .. repeated measures or Within-subjects


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