Final answer:
The symbol HR represents the hazard ratio in survival analysis, which compares the probability of an event occurring in different groups over time. HR = 1.0 means no difference in hazard rates, HR > 1.0 means higher hazard rate in the first group, and HR < 1.0 means lower hazard rate in the first group.
Step-by-step explanation:
In statistical analysis, the symbol HR represents a statistic called the hazard ratio. The hazard ratio is used in survival analysis to compare the probability of an event occurring in different groups over time. It is a ratio of the hazard rates, where the hazard rate is the probability of an event happening at a particular time given that it has not happened before that time.
a) HR = 1.0 means that there is no difference in the hazard rates between the two groups being compared. The event is equally likely to occur at any given time for both groups.
b) HR > 1.0 means that the hazard rate is higher in the first group compared to the second group. The event is more likely to occur at any given time for the first group.
c) HR < 1.0 means that the hazard rate is lower in the first group compared to the second group. The event is less likely to occur at any given time for the first group.