Researchers want to study the effects of labyrinthectomy with cochlear implantation on hearing, vertigo, and tinnitus. A random sample of medical charts is selected from a cohort of patients who had undergone labyrinthectomy with cochlear implantation in the same ear for intractable vertigo and hearing loss and who had documentation of both preoperative and postoperative audiometric evaluations. Tinnitus is quantified using the Tinnitus Handicap Inventory (THI) before and after the interventions. The THI score ranges from 0 to 100, with higher values indicating greater tinnitus severity. Which of the following statistical tests is most appropriate for comparing preoperative and postoperative THI scores?

Question

Researchers want to study the effects of labyrinthectomy with cochlear implantation on hearing, vertigo, and tinnitus.  A random sample of medical charts is selected from a cohort of patients who had undergone labyrinthectomy with cochlear implantation in the same ear for intractable vertigo and hearing loss and who had documentation of both preoperative and postoperative audiometric evaluations.  Tinnitus is quantified using the Tinnitus Handicap Inventory (THI) before and after the interventions.  The THI score ranges from 0 to 100, with higher values indicating greater tinnitus severity.  Which of the following statistical tests is most appropriate for comparing preoperative and postoperative THI scores?

Quizplus · Accepted Answer

11ec160b_372b_7990_9249_a5665fd33a91_MD0001_00 Variables are broadly classified as qualitative (ie, categorical) or quantitative (ie, continuous) based on their scale of measurement. Qualitative variables (eg, type of treatment, blood type) represent categories or groups, whereas quantitative variables (eg, temperature, glucose levels) represent numerical values. The scale of measurement of the dependent (eg, outcome) and independent (eg, exposures, risk factors) variables in a study determines the correct statistical test for any given situation. A t-test compares the mean of 2 groups. It requires that a quantitative dependent variable (ie, outcome) be evaluated in 2 groups that are classified based upon a categorical independent variable (ie, exposure). In this study: The quantitative dependent variable was the Tinnitus Handicap Inventory (THI) score. The categorical independent variable was the audiometric evaluation (with categories "preoperative" and "postoperative"). A t-test will determine whether there is a statistically significant difference in mean THI scores between the preoperative and postoperative audiometric evaluations. A large, statistically significant difference in mean scores indicates that labyrinthectomy with cochlear implantation is associated with changes in tinnitus (ie, the null hypothesis is rejected). There are 2 types of t-tests: the independent samples t-test (used when 2 groups are independent) and the paired t-test (used with 2 related groups with matched pairs). Matched groups are formed when each observation in one group is paired with an observation from the other group. Examples include a study in which individuals have been assessed twice (eg, before and after an intervention) and one in which 2 groups of individuals have been matched based on certain attributes (eg, age, severity of disease). In this case, THI scores are assessed twice for each patient (preoperative and postoperative audiometric evaluations); therefore, a paired t-test is used. (Choice A) The analysis of variance (ANOVA) test compares the mean of ≥3 independent groups, as in a study comparing serum ferritin concentrations (ie, quantitative variable) in children (age 0-17), adults (age 18-59), and seniors (age ≥60). (Choice B) The chi-square test evaluates the association between 2 categorical variables, as in a study evaluating the association between sex (ie, "male" and "female") and myocardial infarction (ie, presence or absence). (Choice C) A correlation analysis uses the correlation coefficient to describe the linear relationship between 2 quantitative variables, as in a study evaluating the linear relationship between hours of sleep and irritability score. (Choice D) Meta-analysis is a statistical technique used to combine and analyze data from several studies to conduct an analysis with a greater statistical power than that of the individual studies. Educational objective: The paired t-test compares the mean of 2 related groups. The test requires that a quantitative dependent variable (ie, outcome) be evaluated in 2 related (ie, matched, paired) groups. __________ References: The differences and similarities between two-sample t-test and paired t-test. (http://www.ncbi.nlm.nih.gov/pubmed/28904516)

Researchers Want to Study the Effects of Labyrinthectomy with Cochlear Implantation