Test Bank For Biostatistics for the Biological and Health Sciences 2nd Edition Author(s) Marc M. Triola; Mario F. Triola; Jason Roy

Chapter 14, "Survival Analysis," from Biostatistics for the Biological and Health Sciences, 2nd Edition by Marc M. Triola, Mario F. Triola, and Jason Roy: What is the primary focus of survival analysis? A) To estimate the average time until an event occurs B) To compare means across multiple groups C) To determine the correlation between two continuous variables D) To analyze categorical data Answer: A Rationale: Survival analysis primarily focuses on estimating the time until a specific event, such as death or failure, occurs. In survival analysis, what does the term "censoring" refer to? A) Excluding participants from the study B) The loss of participants before an event occurs C) Not observing the event during the study period D) Analyzing data without accounting for missing values Answer: C Rationale: Censoring refers to situations where the event of interest has not occurred by the end of the study period, leading to incomplete data. Which of the following statistical methods is commonly used in survival analysis? A) Linear regression B) Kaplan-Meier estimator C) Chi-square test D) ANOVA Answer: B Rationale: The Kaplan-Meier estimator is widely used to estimate survival functions and visualize survival data. What does the log-rank test compare in survival analysis? A) Means of two independent samples B) Variances across multiple groups C) Survival curves of two or more groups D) Censoring rates among groups Answer: C Rationale: The log-rank test is used to compare the survival curves of two or more groups to determine if there are significant differences in survival times. In the context of survival analysis, what is the "hazard function"? A) The probability of an event occurring over time B) The average time until an event occurs C) The instantaneous rate of occurrence of an event D) The cumulative probability of survival over time Answer: C Rationale: The hazard function represents the instantaneous rate of occurrence of the event of interest at a given time point. Which of the following is an assumption of the Cox proportional hazards model? A) The survival distributions must be normal B) The hazard ratios remain constant over time C) There is no censoring in the data D) The sample size must be large Answer: B Rationale: The Cox proportional hazards model assumes that the hazard ratios remain constant over time, allowing for the comparison of the effect of covariates on survival. What type of data is most appropriate for survival analysis? A) Continuous data B) Categorical data C) Ordinal data D) Time-to-event data Answer: D Rationale: Survival analysis is specifically designed for time-to-event data, where the focus is on the time until an event occurs. In survival analysis, which method would you use to visualize the survival function? A) Box plot B) Histogram C) Kaplan-Meier curve D) Scatter plot Answer: C Rationale: A Kaplan-Meier curve is used to visualize the survival function over time, illustrating the proportion of subjects surviving at different time points. What is a common reason for conducting a survival analysis? A) To identify trends in nominal data B) To evaluate the efficacy of a treatment over time C) To compare means across groups D) To test the independence of categorical variables Answer: B Rationale: Survival analysis is often conducted to evaluate the efficacy of treatments or interventions over time, particularly in clinical research. Which of the following terms refers to the time until the first occurrence of an event? A) Cumulative incidence B) Survival time C) Event time D) Time-to-event Answer: D Rationale: "Time-to-event" refers to the time until the first occurrence of an event, which is a key focus of survival analysis. What does the term "survival function" represent in survival analysis? A) The probability of survival at a specific time point B) The average time until the event occurs C) The likelihood of censoring occurring D) The total number of events observed Answer: A Rationale: The survival function represents the probability of surviving beyond a specific time point, providing insights into survival rates over time. In survival analysis, what does the term "median survival time" indicate? A) The time at which 50% of subjects have experienced the event B) The average time to event occurrence C) The time when censoring occurs D) The range of survival times in the study Answer: A Rationale: Median survival time indicates the time at which 50% of subjects have experienced the event of interest, providing a central measure of survival. What type of model is the Cox proportional hazards model? A) Parametric model B) Nonparametric model C) Semi-parametric model D) Linear regression model Answer: C Rationale: The Cox proportional hazards model is a semi-parametric model that does not assume a specific form for the baseline hazard function.