© John Wiley & Sons, Inc.

FIGURE 21-3: A partially completed life table to analyze the survival times shown in Figure 21-2.

To fill in the table shown in Figure 21-3:

Put the description of the time interval that defines each slice into Column A.

Enter the total number of participants alive at the start into Column B in the 0–1 yr row.

Enter the counts of participants who died within each time slice into Column C (labeled Died).

Enter the counts of participants who were censored during each time slice into Column D (labeled

Last Seen Alive).

After you’ve entered all the counts, the spreadsheet will look like Figure 21-3. Then you perform the

calculations shown in the Formula row at the top of the figure to generate the numbers in all the other

cells of the table. (To see what it looks like when the table is completely filled in, take a sneak peek at

Figure 21-4.)

Columns B, C, and D

Column B includes the number of participants known to be alive at the start of each year after surgery.

This is equal to the number of participants alive at the start of the preceding year minus the number

who died (Column C) or were censored (Column D) during the preceding year. Here’s the formula,

written in terms of the column letters: B for any year = B – C – D from the preceding year.

Here’s how this process plays out in Figure 21-3:

Out of the ten participants alive at the start, one died and one was last seen alive during the first

year. This means eight participants (10 – 1 – 1) are known to still be alive at the start of the second

year. The missing participant is #5, who was LFU during the first year. They are censored and not

counted in any subsequent years.

Zero participants died or were last seen alive during the second year. So, the same eight

participants are still known to be alive at the start of the third year.

Calculations continue the same way for the remaining years.

Column E

Column E shows the number of participants at risk for dying during each year. You may guess that this

is the number of participants alive at the start of the interval, but there’s one minor correction. If any

were censored during that year, then they weren’t technically able to be observed for the entire year.