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## Measurement, statistics and appraisal

Respond to post below, explain why you agree or disagree with writer. Support your response with at least one reference.
Post:
Independent variables refer to the variables that are manipulated by a researcher in an experimental study in
order to determine their relationship to an observed phenomenon (Schmidt, 2018). Dependent variables are
the outcome variables, which take on various values in response to the independent variables (Schmidt, 2018).
Simultaneously, extraneous variables refer to the variables that can influence the relationship between the
dependent and independent variables (Schmidt, 2018). They are not known or foreseen (and cannot be known
or foreseen) at the beginning of the research. However, extraneous variables can be controlled either through
statistical procedures or research design.
Extraneous variables are a serious challenge to both external and internal validity of the research. Generally,
the experimenter can control the extraneous variables in several ways. First, the method of randomization
provides the ability for the researcher to control extraneous variables by randomly assigning the subjects to
various control and treatment groups (Tucker-Drob, 2011). This allows considering them statistically equal for
all variables at the start of the research. Although it does not mean that they are equal in all ways, if the
assignment has been performed properly, the probability of their being equal becomes relatively higher.
Second, the process of matching is an effective way of controlling extraneous variables that allows to get as
much control of them as possible. It is used when it is impossible to perform randomization as the research
groups contain some important variables or when they are too small. In such cases, subjects can be matched
for those crucial variables. Therefore, the researcher selects them to match each other for the specified
variables. The equality of the groups at the outset is ensured by assigning the matched subjects to the
research group and one subject to the control group. Moreover, matching adds serious subjectivity into sample
selection and it is time consuming. At the same time, the extraneous variables can add an alternative
explanation of the research results, and therefore must be controlled.
References:
Grand Canyon University (Ed). (2018). Nursing research: Understanding methods for best practice. Retrieved
from https://lc.gcumedia.com/nrs433v/nursing-research-understandingmethods-for-bestpractice/v1.1
Tucker-Drob E. M. (2011). Individual differences methods for randomized experiments. Psychological methods,
16(3), 298–318. doi:10.1037/a00
Ackley, B. J., Swan, B. A., Ladwig, G., & Tucker, S. (2008). Evidence-based nursing care guidelines: Medicalsurgical interventions. St. Louis, MO: Mosby Elsevie