title: How to get the 50% survival event time in a Survival Analysis
body: <p>I am putting together a survival analysis that gets run through a shiny app, and as such the output will be changing frequently.  I have code that is running the survival analysis, and then printing the summary at for every 26 months (randomly chosen number as of right now), and doing that 10 times.</p>
  
  <pre><code>km_fit &lt;- survfit(Surv(Life_Time_Months, Is_Closed) ~ 1, data = My_Data)
  summary(km_fit, times = c(25 * (1:10)))
  </code></pre>
  
  <p>The output of the summary looks approximately like this:</p>
  
  <pre><code>time n.risk n.event survival std.err lower 95% CI upper 95% CI
     26  99910   19897    0.841 0.00104        0.839        0.843
     52  72512   15084    0.704 0.00134        0.701        0.707
     78  52153   10037    0.598 0.00150        0.595        0.601
    104  39170    5106    0.534 0.00159        0.531        0.537
    130  30783    3394    0.484 0.00165        0.481        0.487
    156  24563    2404    0.444 0.00171        0.440        0.447
    182  19351    1625    0.412 0.00176        0.408        0.415
    208  15463    1154    0.385 0.00182        0.382        0.389
    234  11924     796    0.363 0.00187        0.359        0.367
    260   9179     512    0.346 0.00194        0.342        0.349
  </code></pre>
  
  <p>Instead of having 10 printed results at multiples of 26, I would really like just one result that has when the percentage of survival is at 0.5, or as close as possible.</p>
  
  <p>How would I go about doing this?</p>