A question about the conditional probability of rain - see details?

Question

Suppose the probability that it rains in a particular area on any given day is P, observed from historical records. If it rains in this area today, is the probability that it will rain in this area tomorrow >, =, or < P? Will this question have different answers for different areas?

Answer 1

It would stay the same, I believe.  One day wouldn&#039;t affect it that much.

Answer 2

You are talking about a statistical forecast. Therefore, the answer depends on the statistical model being used.

In a Markovian type of analysis, on which you study the sequences of events, it would matter, and it could go both ways. It would depend if, in your area, rainy days are typically followed by rainy days or by sunny days. In this case, it does depend on the region you are studying. However, being rain a somewhat persistent phenomenon, it is likely that raining today would tend to increase the rain probability for tomorrow.

Now, you may determinje the probability of rain on a given day, based on the historical series for that day, along the year. In this case, the rain of today does not affect the probability for tomorrow. It only changes the probability for this day, on next year.

You see? Statistics can be done many ways. In any case, you need to know what you are doing.

Finally, it is important to say that dynamical models are much better than statistical ones to forecast rain.