> The angle brackets are defined as a running average over the 365 days, so this quantity involves data going back twice as long: 730 days. Furthermore, the ‘link strength’ involves the above expression where $\tau$ goes up to 200 days.

> So, taking their definitions at face value, Ludescher _et al_ could not actually compute their ‘link strength’ until 930 days after the surface temperature data first starts at the beginning of 1948. That would be late 1950. But their graph of the link strength starts at the beginning of 1950!

Your program [ludescher.R](https://github.com/azimuth-project/el-nino/blob/master/R/grj/ludescher.R) wants to eat data from a file Pacific-1950-1979.txt. So I guess you using temperature data that starts in 1950, rather than 1948.

That goes along with what Ludescher _et al_ say: they're using "atmospheric temperature data for the 1950–2011 period." But even if they didn't fall into the "running average of running averages" trap, with data starting in 1950 their graph could only start 565 days later! Right?

That would be around 1952. And your graph _does_ start in 1952, right?

So, my theory is that despite what they _say_, they actually use data starting in 1948! That would let their graph start in 1950.

I suppose all this is more annoying than important. But I'm running ludescher.R now, so this stuff is on my mind.