Editing Construct validity (section)

==Threats to construct validity==
Apparent construct validity can be misleading due to a range of problems in hypothesis formulation and experimental design.
* '''Hypothesis guessing''': If the participant knows, or guesses, the desired end-result, the participant's actions may change.<ref>McCroskey, J. C., Richmond, V. P., & McCroskey, L. L. (2006). An introduction to communication in the classroom: The role of communication in teaching and training. Boston: Allyn & Bacon.</ref> An example is the [[Hawthorne effect]]: in a 1925 industrial ergonomics study conducted at the Hawthorne Works factory outside Chicago, experimenters observed that both lowering ''and'' brightening the ambient light levels improved worker productivity. They eventually determined the basis for this paradoxical result: workers who were aware of being observed worked harder no matter what the change in the environment.
* '''Bias in experimental design''' (intentional or unintentional). An example of this is provided in [[Stephen Jay Gould]]'s 1981 book "[[The Mismeasure of Man]]".<ref>Gould, S. J. (1996). The Mismeasure of Man. 2nd edition. New York: W. W. Norton & Company.</ref> Among the questions used around the time of World War&nbsp;I in the battery used to measure intelligence was "In which city do the Dodgers play?" (they were then based in Brooklyn). Recent immigrants to the US from Eastern Europe unfamiliar with the sport of baseball got the answer wrong, and this was used to infer that Eastern Europeans had lower intelligence. The question did not measure intelligence: it only measured how long one had lived in the US and become accultured to a popular pastime.
* '''Researcher expectations''' may be communicated unintentionally to the participants non-verbally, eliciting the desired effect. To control for this possibility, [[double-blind]] experimental designs should be used where possible. That is, the evaluator of a particular participant should be unaware of what intervention has been performed on that particular participant or should be independent of the experimenter.
* '''Defining predicted outcome too narrowly'''.<ref>{{cite journal | author = MacKenzie S. B. | year = 2003 | title = The dangers of poor construct conceptualization | journal = Journal of the Academy of Marketing Science | volume = 31 | issue = 3| pages = 323–326 | doi=10.1177/0092070303031003011| citeseerx = 10.1.1.417.7311 | s2cid = 5930358 }}</ref> For instance, using only [[job satisfaction]] to measure happiness will exclude relevant information from outside the workplace. 
* '''[[Confounding|Confounding variables]]''' (covariates): The root cause for the observed effects may be due to variables that have not been considered or measured.<ref>{{cite journal |author1=White D. |author2=Hultquist R. A. | year = 1965 | title = Construction of confounding plans for mixed factorial designs | journal = The Annals of Mathematical Statistics | volume = 36 | issue = 4 | pages = 1256–1271 | doi=10.1214/aoms/1177699997 | doi-access = free }}</ref>

An in-depth exploration of the threats to construct validity is presented in Trochim.<ref name="Trochim, William M.">[http://www.socialresearchmethods.net/kb/consthre.php Threats to Construct Validity], Trochim, William M. The Research Methods Knowledge Base, 2nd edition.</ref>