Instrumentation Threats
When an observed effect is caused by a difference in the way
the pretest and posttest are measured, rather than the impact of the treatment
that was implemented, this is called an instumentation threat. This can
happen when the measurement depends on observers who become more experienced
over time, or if the observers change from the pretest to the posttest.
This can also happen if the measurement test has a shift in metric at certain
points, for example, if a scale is less sensitive at the top or the bottom
than it is in the middle.
How do you think a comparison group can alleviate this threat to internal
validity?
Back
Home | Name
That Threat | Trochim Home
| Research
Methods Tutorials
History | Maturation
| Mortality | Regression
| Testing
Copyright © 1997 Wendy
Martin. All rights reserved.