Work
Average length of a set
A set averages out the noise of any single line. A mean below the phone threshold means most of the set will be read whole, which is the figure worth watching.
The Formula
average length = total characters across the set / number of lines
A set averages out the noise of any single line. A mean below the phone threshold means most of the set will be read whole, which is the figure worth watching.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| n | Lines in the set | count | How many candidates were generated. |
| L_i | Length of line i | characters | Characters in one candidate. |
| L | Mean length | characters | The average across the set. |
What Each Symbol Means
ncount
Lines in the set
How many candidates were generated.
L_icharacters
Length of line i
Characters in one candidate.
Lcharacters
Mean length
The average across the set.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to write email subject lines page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Write Email Subject Lines, filed under Everyday Life. Every number the guide produces comes from substituting into this one line.