Re: [ai-geostats] Re: Sill versus least-squares classical variance estimate
- Hi Digby and All,
I did a little experiment on the idea that Digby mentioned: The sill will
estimate the population variance, but found it not true in my experiment:
1. I generated a set of one-dimentional data with 27 points on regular
unit spacings, which I'd like to take it as the true, or population
value. On purpose, I generate the data so it has an influence range of
three length units.
2. I calculated the experimental variogram. Notice that the variogram is
the population variogram. The sill value is around 2.8.
3. But the population variance is 2.39, lower than the sill value.
This confirms my doubt about using sill value as the estimate of
population variance, since I calculate the variogram and variance based on
all data points. Please tell me what you think. The data I generated are