Measurement, Statistics, and Appraisal Essay

Measurement, Statistics, and Appraisal Essay

1. Compare independent variables, dependent variables, and extraneous variables. Describe two ways that researchers attempt to control extraneous variables. Support your answer with peer-reviewed articles. 2. Describe the \”levels of evidence\” and provide an example of the type of practice change that could result from each.

Measurement, Statistics, and Appraisal

Independent variables, dependent variables, and extraneous variables

A variable is an entity that varies or an entity whose value varies. According to Kaliyadan and Kulkarni (2019), in an experimental study context, the dependent variables, also referred to as outcomes variables have a direct correlation with the primary outcome of the research study.  The independent variable, at times known as the explanatory variable, is an entity that is not affected by the experiment per se but which might be manipulated to influence the dependent variable.  For example, in a clinical study on wound effect of dressing on wound healing would be the dependent variable while the form of dressing would be independent valuable. Measurement, Statistics, and Appraisal Essay

Extraneous variables also referred to as confounding variables are extra variables that confound or confuse the correlation between the independent and dependent variables and can lead to a false association between these variables (Kaliyadan &  Kulkarni, 2019).  For instance, in a study of wound dressing on wound healing, the presence of diabetes and patient age would be extraneous variables.

Two ways that researchers attempt to control extraneous variables

Extraneous variables can have a  negative impact on internal validity as well as the external validity of a study.  Researchers use randomization/use of randomized experimental design and to control extraneous variables.  Caparlar and Donmez (2016) indicate that the selection of study participants should be random to prevent unconscious or conscious manipulations in the selection of participants.  Randomization strengthens the design of the study and enhances the determination of trustworthy scientific knowledge. Measurement, Statistics, and Appraisal Essay

Randomization is the utilization of the probability theory utilized to assign study subjects to diverse treatment groups.  It is a scheme by which the participants in the research study are assigned to the numerous treatment groups under study.  According to Baghbaninaghadehi et al. (2016), a randomized experimental design utilize a systematic methodology that permits controlling for confounder/extraneous variables and permits the researcher to make causal inferences with the maximum level of confidence.  Randomization permits the utilization of probability theory and increases the possibility that alterations in the dependent variable are attributable to the independent variables instead of confounding variables or extraneous factors; thus,  lessening the likelihood of confounding bias.

Another way that researchers can control extraneous variables is by holding them constant.  This is achieved by holding task or situation variables constant through testing all study subjects in the same location, offering them the same instructions, and similarly treating them. Flannelly et al. (2018) indicate extraneous variables must be properly controlled because they are extraneous to the aim of the research study and they can confound how the independent variable influences the dependent variable.  If the researcher fails to control extraneous variables, they undermined his/ her ability to plausibly draw a causal inference that the effect of manipulation of an experiment is, in reality, the outcome of the independent variable.Measurement, Statistics, and Appraisal Essay

Levels of evidence

Evidence-based practice involves finding evidence and utilizing this evidence to make a clinical decision. An evidence pyramid visually depicts the strength of evidence of diverse research designs. Level 7 evidence is the least reliable evidence that comes from editorials, anecdotes, opinions, and ideas  While personal experience, opinions, and ideas may be useful, they might not be easily explained or transferrable. They are similar to anecdotal evidence, which is consistent with or based on, observations or reports of typically unscientific observers.


Level 6 is evidence obtained from case reports, case series, and controlled studies. According to Ingham-Broomfield (2016), a case report or case-controlled study is a thorough study of an individual unit that might include, for instance, a group or one family.  Level 5 evidence comes from cohort studies. A cohort is a study in which study participants are categorized in accordance with the degree to which they are exposed to risk factors. The researcher then follows up with the participants over a certain duration to examine the possible incidence of disease, For example,  a cohort study comparing the rates of post-operative infection between two theaters; one where nurses wore masks and one where nurses did not can be used to promote mask-wearing among surgical nurses.

Level 4 is evidence from Random Control Trials(RCTs)According to Ingham-Broomfield ( 2016) random Control trials is an experimental type of research where study participants are randomly assigned into at least two diverse groups with every group being given a different I treatment/intervention. The effects of the interventions are then gauged.  For example, a RCT can evaluate physical activity recommendations among patients with low and high health literacy. Measurement, Statistics, and Appraisal Essay

Level 3 evidence is obtained from critically appraised individual articles. Critical appraisal evaluates the outcomes for evidence in relation to the effectiveness of an individual research study. Authors of articles that are critically appraised assess and synopsise individual synopsis. Level 2 evidence is obtained from critically appraised topics. Several journals have sections highlighting papers that have been critically appraised and tell the reader the strength of the evidence. Authors of topics that have been critically appraised assess and synthesize several research studies (Ingham-Broomfield, 2016).  For example, authors can appraise the benefits of the hydraulic prosthetic ankle compared to non-hydraulic prosthetic ankles on patients with transtibial amputation

Leve1 evidence is the most reliable evidence which is obtained from meta-analysis and systematic reviews. According to Ingham-Broomfield (2016), systematic review involves reviewing existing literature on a certain question through identification,  evaluation,  assortment, and synthesis of superior quality evidence related to a research question.  A meta-analysis provides the greatest level of evidence since it is a collective analysis of numerous randomized controlled trials. Glasofer and Townsend (2019 indicate that the methodologies used in meta-analysis or systematic reviews lessen bias and assist recognize causal-effect relationships.  For example, a systematic review can be used to determine the association between nurses’ well-being and burnout with patient safety. Measurement, Statistics, and Appraisal Essay


Baghbaninaghadehi, F., Armijo-Olivo, S., & Woodhouse, L. (2016).  Fundamentals of Randomization in Clinical Trial.  International Journal of Advanced Nutritional and Health Science, 4(1), 174-187.

Caparlar, C. O., & Donmez, A. (2016). What is Scientific Research and How Can it be Done?  Turkish Journal of Anaesthesiology and   Reanimation, 44(4), 212-218. doi: 10.5152/TJAR.2016.34711

Flannelly, K. J., Flannelly., L. T., & Jankowski, K. R. (2018). Threats to the Internal Validity of Experimental and Quasi-Experimental Research in Healthcare. Journal of Health Care Chaplaincy, 24(3), 1-24. doi: 10.1080/08854726.2017.1421019

Glasofer, A., & Townsend, A. B. (2019). Determining the level of evidence: Experimental research appraisal.  Nursing Critical Care, 14(6), 22-25. doi: 10.1097/01.CCN.0000580120.03118.1d

Ingham-Broomfield, R. (2016). A nurses’ guide to the hierarchy of research designs and evidence. Australian Journal of Advanced Nursing, 33(3), 38-43.

Kaliyadan, F., & Kulkarni, V. (2019). Types of Variables, Descriptive Statistics, and Sample Size.  Indian Dermatology Online Journal, 10(1), 82-86. doi: 10.4103/idoj.IDOJ_468_18

Measurement, Statistics, and Appraisal Essay