By using a classroom setting, the study has more control of the variance of the experiment and avoids extraneous variables
Control refers to the researcher's efforts to remove the influence of any extraneous variable
(other than the independent variable itself) that might affect scores on the dependent variable" (p.
In the case of teenage smoking, such an extraneous variable
might be the discretionary income level among this teen population, which could have facilitated both smoking and moviegoing.
There may have been other extraneous variables
that had an effect on the outcome.
Although the variability associated with physiological responses can obscure real findings, it can also lead to inaccurate conclusions when extraneous variables
that affect the physiological system of interest are not evenly distributed across experimental conditions.
of the type of sampling performed, the possible experimental conditions, the context and circumstances in which the study is performed, and the procedures used to control the extraneous variables
is therefore an essential requirement in any research.
Qualitative methods attempt to capture as much information and variability as possible to understand and describe, rather than to remove, extraneous variables
and statistically represent other populations.
There are many extraneous variables
than can affect a player's form on the big stage.
This design controlled for extraneous variables
that could have been revealed if the intervention had begun simultaneously (Tawney & Gast, 1984).
In any experiment, to get accurate results one must control for the extraneous variables
that might have a negative impact on whatever one is trying to examine or measure.
There may also be Extraneous variables
(Polit and Hungler 2013), also known as Confounding variables (White and Millar 2014 p47), which confuse or confound the relationship between the Dependent and Independent variables.
Alo and Cancado write that defining motivation by exclusion--that is, by factors that are outside the operant contingency--is problematic for two reasons: first, because of the unaccounted effects of extraneous variables
and second, because variables that are not part of the n-term contingency that affect responding may not necessarily be motivational.