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Human Impact on Climate does the data support
that there is an effect?
Looking at more data to find significance or not:
Another Case: US Tornado Frequency:
This is the distribution of verified tornadoes in the American
Midwest from the period of 1953--1993:
Is the apparent recent increase significant?
Again the means are similar so we get
Another Case: Urbanization and the Weather
Does Urbanization produce a microclimate in the sense that urban areas are getting warmer.
Here are some results for Washington DC average Tempearture:
Note that the dispersions are all very similar in these periods. The square root of 120 (number of data samples) = 11.
Let's look at the case for Berkeley CA:
So for Berkeley we have: 14.32-13.67/1.5(.27) = .65/.40 = 1.65 --> still not significant but a lot more significant than the case for Washington DC.
This indicates that Berkeley is a better site for this study than Washington DC since the natural climate variations in DC are more severe and hence the signature of a small effect will be much more difficult to get out of the data.