Cumulative Incidence in Health Sciences
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Questions and Answers

What is the main difference between measuring presence and measuring occurrence of health indicators?

  • Presence measurement is based on prevalence and odds, while occurrence measurement is based on cumulative incidence and incidence rate.
  • Presence measurement is useful for acute health indicators, while occurrence measurement is useful for chronic health indicators.
  • Presence measurement is related to new cases, while occurrence measurement is related to the evolution of the health indicator over time.
  • Presence measurement is useful for time-dependent outcomes, while occurrence measurement is useful for unchanging characteristics. (correct)

    • Which type of health indicator is best measured using prevalence and odds?

  • Time-dependent outcomes
  • Unchanging characteristics
  • Chronic health indicators (correct)
  • Acute health indicators

    • What does cumulative incidence measure?

  • The evolution of a health indicator over time
  • The prevalence and odds of a chronic health indicator
  • The presence of a health indicator among individuals
  • The occurrence of new cases related to a health indicator over time (correct)

    • When is measuring occurrence particularly useful?

    <p>For time-dependent outcomes</p> Signup and view all the answers

    What is the difference between cumulative incidence and incidence rate?

    <p>Cumulative incidence measures new cases over a specific period, while incidence rate measures the evolution of a health indicator over time.</p> Signup and view all the answers

    Which measurement is particularly useful for assessing unchanging characteristics like asthma or diabetes?

    <p>Measuring prevalence</p> Signup and view all the answers

    What does the p-value of 0.548 indicate?

    <p>No evidence against the null hypothesis</p> Signup and view all the answers

    In epidemiology, what is the incidence rate?

    <p>The number of new cases per person-time at risk unit</p> Signup and view all the answers

    What is the main difference between cumulative incidence (CI) and incidence rate (Ir)?

    <p>CI depends on the total time at risk, while Ir depends on the proportion of new cases in the cohort</p> Signup and view all the answers

    How can a confidence interval for the incidence rate (Ir) be obtained?

    <p>Based on a Poisson distribution or an approximation based on the normal distribution</p> Signup and view all the answers

    What distribution is assumed for the time to the beginning of the illness when estimating cumulative incidence?

    <p>Exponential distribution</p> Signup and view all the answers

    What does the Wald test in epidemiology compare for two incidence rates?

    <p>The expectation and variance of new cases in each population area</p> Signup and view all the answers

    What value is compared to a chi-squared distribution in the Wald test for comparing two incidence rates?

    <p>(I1 ∆t0 - I0 ∆t1)2 / Var(Ij)</p> Signup and view all the answers

    What does the p-value indicate in the context of the Wald test for comparing two incidence rates?

    <p>The probability that there is no difference in the number of new cases between the two populations</p> Signup and view all the answers

    What does it mean if Ir could be time varying in epidemiological terms?

    <p>The probability of getting the disease changes over time</p> Signup and view all the answers

    How is cumulative incidence (CI) estimated in epidemiology?

    <p>By using the proportion of new cases in the cohort</p> Signup and view all the answers

    What is required to estimate incidence rate (Ir) in epidemiological studies?

    <p>Having information on both the number of new cases and total time at risk for each individual in the study</p> Signup and view all the answers

    In epidemiology, what does Ir represent?

    <p>The expansion speed of a disease in a population at a particular time point</p> Signup and view all the answers

    What is the prevalence (P) of a given disease D within a given time interval of length $t$?

    <p>The proportion of individuals affected by D in the population of interest</p> Signup and view all the answers

    What is the main limitation of the approximated confidence interval formula (1)?

    <p>It may give an upper bound of the confidence interval higher than 1 or a lower bound lower than 0</p> Signup and view all the answers

    In which type of studies is it not possible to estimate prevalence?

    <p>A and B</p> Signup and view all the answers

    What statistical tests can be used to compare prevalence in two different populations?

    <p>binom.test and prop.test</p> Signup and view all the answers

    Which measure is particularly useful for assessing unchanging characteristics like asthma or diabetes?

    <p>Prevalence</p> Signup and view all the answers

    What is the main difference between measuring presence and measuring occurrence of health indicators?

    <p>Presence refers to the existence of a health indicator, while occurrence refers to the frequency of its appearance</p> Signup and view all the answers

    $CI = \frac{I}{N0}$, where $I$ is the number of new cases and $N0$ is the disease-free population size. What does $I$ represent in this formula?

    <p>$I$ represents the total number of new cases within a given time interval</p> Signup and view all the answers

    Which measure is sensitive to the duration of the disease in an individual?

    <p>Prevalence</p> Signup and view all the answers

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