I have thirty three SO2 readings from sensing equipments installed at 33 locations spread over a large region (one observation per city). The sample size is fixed and can not be increased because of the number of equipments installed. Now (geo)-statistically it's a quite a small sample as many authors state that the sample size should be between 100-150 to get reliable variogram. Can somebody guide me as to how to deal with such a small data? Further, it actually will be a spatio-temporal analysis, but at each time instant again there are 33 observations. What I actually want to ask is that what is the impact of increasing the area size (resolution), whereas the number of overall sample points still remains the same, on variogram estimation?
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In the above both cases the relative distance between different pairs still remain the same. That's dist(z_1, z_2)/dist(z_2, z_3) remain the same on both scales.
Variogram estimation does not get any better if you increase area size or resolution, but do not increase the amount of sample data from which you compute the sample variogram.