**Why is the P/E on this site different than what is reported by S&P and
other sites?**

The P/Es listed on many other sites are based on earnings from the previous year only.

The figures on multpl.com are the PE10 or Shiller PE. They are the price to
average earnings from the past ten years. Because this factors in earnings
from the previous ten years, it is less prone to
wild swings in any one year.

**What is the P/E 10? How is it calculated?**

To calculate P/E10:

- Look at the yearly earning of the S&P 500 for each of the past ten years.
- Adjust these earnings for inflation, using the CPI (ie: quote each earnings figure in 2012 dollars)
- Average these values (ie: add them up and divide by ten), giving us e10.
- Then take the current Price of the S&P 500 and divide by e10.

**Are you Robert Shiller? Is this site affilated with Yale
University?**

I am not Robert Shiller. Neither Dr Shiller nor Yale have any affiliation with multpl.com.

However, Dr Shiller has published nice data sets on his site, some of which are used to compute the charts on this site.