What is the effective number exposed to risk of dying in the 13- to 24-month interval? Use the following table to answer the question. Survival of Patients With Metastatic Cancer Z Following Diagnosis
\(\begin{array}{|l|l|l|l|l|l|l|l|}
\hline \begin{array}{l}
\text { Interval } \
\text { since } \
\text { beginning } \
\text { treatment } \
\text { (months) }
\end{array} & \begin{array}{l}
\text { Alive at } \
\text { beginning } \
\text { of } \
\text { interval }
\end{array} & \begin{array}{l}
\text { Died } \
\text { during } \
\text { interva } \
1
\end{array} & \begin{array}{l}
\text { Withdre } \
\text { w during } \
\text { interval }
\end{array} & \begin{array}{l}
\text { Effective } \
\text { number } \
\text { exposed } \
\text { to risk of } \
\text { dying }
\end{array} & \begin{array}{l}
\text { Proporti } \
\text { on who } \
\text { died } \
\text { during } \
\text { interval }
\end{array} & \begin{array}{l}
\text { Proportion } \
\text { who did not } \
\text { die during } \
\text { interval }
\end{array} & \begin{array}{l}
\text { Cumulative } \
\text { proportion } \
\text { who } \
\text { survived } \
\text { from } \
\text { enrollment } \
\text { to end of } \
\text { interval }
\end{array} \
\hline x & I_{x} & d_{x} & W_{x} & I_{x}^{\prime} & q_{x} & p_{x} & P_{x} \
\hline 1-12 & 200 & 10 & 40 & & & & \
\hline 13-24 & 150 & 20 & 30 & & & & \
\hline 25-36 & 100 & 30 & 20 & & & & \
\hline 37-48 & 50 & 40 & 10 & & & & \
\hline
\end{array}\)

Question

Quizplus · Accepted Answer

The effective number exposed to risk of dying in the 13- to 24-month interval can be calculated using the formula: $I_x^{\prime} = I_x - \frac{1}{2}W_x$, where $I_x$ is the number alive at the beginning of the interval and $W_x$ is the number who withdrew during the interval. For the 13-24 month interval, $I_x = 150$ and $W_x = 30$, so $I_x^{\prime} = 150 - \frac{1}{2}(30) = 150 - 15 = 135$.

What Is the Effective Number Exposed to Risk of Dying