History Effects

Authors

Affiliations

Nate Yomogida, B.S., SPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, B.S., SPT

Doctor of Physical Therapy

B.A. in Neuroscience

History effects refer to a systematic error cause when a study recruits individuals but neglects to monitor or report certain variables that could impact results. History effects has the potential to overestimate or underestimate treatment effects.

Example

• Patients are included in a study regardless of type or dose of analgesic medications, which are not standardized, monitored, or reported
• Describes history effects, which have the potential to overestimate treatment effects if analgesic medication uses higher in the treatment group compared to the control group

How does this effect the results?

• Whichever group has a higher dose and prevalence of analgesics will have improved results.
• If the control group uses more analgesics, then the treatment effects will be underestimated.
• If the experimental group receives more analgesics, the treatment effects will be overestimated.

Prevention

History effects can be ruled out using a control group.