T-Test Discussion Article the purpose of this article was to evaluate the efficacy of two different respiratory training regimens and respiratory function in individuals who had completed coronary bypass surgery and were also in a phase two cardiac rehabilitation program. Utilizing a quazi-experimental study process, the researchers prospectively evaluated twenty-four participants over twelve weeks. The participants were divided into two equal groups of twelve, each group participating in different respiratory exercises and evaluated (before and after exercise) regarding inspiratory / expiratory pressures, peak oxygen consumption, and quality of life scores (Hermes, Cardoso, Gomes, Santos, Vicente, Pereira, Barbosa, & Albuquerque, 2015).Inclusion criteria for participation in the study included individuals who underwent Coronary Artery Bypass Grafting within three weeks of the study with no complications, non-smokers, and agreement to participate in the study. Exclusion criteria for participation in the study included COPD, unstable angina, CHF, acute pericarditis / myocarditis, uncontrolled HTN, severe neuro or orthopedic disorders, and uncontrolled diabetes (Hermes et. al., 2015).Individuals randomly placed into group one of the study underwent twelve weeks of normal cardiac rehabilitation programming as well as inspiratory muscle training regimens. Those randomly assigned to group two underwent only a twelve cardiac rehab program. Each group received a sixty-minute rehab session twice per week for a total of twelve weeks. Both groups were evaluated by blinded investigators to control for bias (Hermes et. al., 2015).Average cardiac rehab program sessions consisted of thirty minutes of aerobic exercises with twenty minutes of resistance exercises and ten minutes stretching and relaxation. Individuals in group one also participated in Inspiratory Muscle Training. This consisted of three sets of repetitious breathing utilizing an IMT Threshold machine. Participants were prompted to use the machines to maintain thirty percent of maximal inspiratory pressure during breathing cycles with the machine (Hermes et. al., 2015).Breathing pressures were assessed using a digital pressure manometer. Functional capacities were assessed using the Bruce Protocol with treadmill stress testing. Quality of life was assessed using the Minnesota Living with Heart Failure Questionnaire. Statistical analysis of the data was completed using SPSS 20.0 and variable normality was assessed using the Shapiro – Wilk test. Student’s t-test was used to compared the results before and after interventions were completed (Hermes et. al., 2015).Analysis of ResultsThe authors found that the patients who participated in the rehabilitation program paired with the IMT fared much better after twelve weeks when compared to group one. The stated P value for their evaluation was P < 0.05 as statistical significance. Comparing the two groups in expiratory pressure alone; the values for group one were 87.3 +/- 11.0 cmH2O pretest and 89.8 +/- 10.5 cmH2O posttest. Group two tests were 86.6 +/- 25.9 cmH2O pretest and 108.1 +/- 17.1 cmH2O posttest. The P values derived from their Student’s t-test for group one expiratory pressures were P<0.001, meaning that both results were highly statistically significant (Hermes et. al., 2015).While their use of a Student’s t-test is appropriate, the authors did not directly specify acceptance or denial of a null hypothesis for their experiment, nor did they elaborate on their initial research hypothesis. The authors simply stated that they were investigating, “the efficacy of a short-term inspiratory muscle training program associated with combined aerobic and resistance exercise on respiratory muscle strength, functional capacity and quality of life in patients who underwent coronary artery bypass and are in the phase II cardiac rehabilitation program” (Hermes et. al., 2015). The authors did not make a prediction towards their results, which is the idea behind P values (Harris & Taylor, 2014). They only stated an objective that cannot be accepted nor declined as can a hypothesis or null hypothesis.The authors use of a Student’s t-test was appropriate due to their data containing normalized statistical skew along with proper determination of skew through use of a Shapiro – Wilk test (“NIST/SEMATECH e-Handbook of Statistical Methods,” 2013). This test for normality allowed the researchers to determine whether their data was truly normalized and whether their use of a t-test for their parametric statistics was warranted (Harris & Taylor, 2014). The researchers also used the t-test to analyze only two samples, groups one and two. Two samples, both containing normal skew, exemplifies proper use of t-tests and reveals a high probability that the samples are derived from populations with the same mean value (Harris & Taylor, 2014).References(Oct. 30, 2013). NIST/SEMATECH e-Handbook of Statistical Methods. Retrieved from http://www.itl.nist.gov/div898/handbook/prc/section2/prc213.htmHarris, M., & Taylor, G. (2014). Medical statistics made easy. Banbury: Scion publishing.Hermes, B. M., Cardoso, D. M., Gomes, T. J., Santos, T. D., Vicente, M. S., Pereira, S. N., Barbosa, V. A., Albuquerque, I. M. (2015). Short-term inspiratory muscle training associated with combined aerobic and resistance training is beneficial in patients undergoing CABG surgery in phase II cardiac rehabilitation program. Revista Brasileira De Cirurgia Cardiovascular. doi:10.5935/1678-9741.20150043
