GGR 270 – Lecture 5 – October 13, 2010

Probability

Studying spatial patterns is a key concern of geographers

oTry to understand what has led to these patterns

Geography is about describing, explaining, and predicting geographic patterns and

processes

Use probability for situations when patterns have some degree of uncertainty

oEx: weather P.O.P

Probability focuses on the occurrence of an event

oWhere one of several outcomes could result

oOutcomes are (and must be) mutually exclusive

Can be thought of as frequency of an event occurring relative to all other outcomes

P(A) = F(A) / F(E) where...

P(A) = Probability of outcome A occurring

F(A) = Absolute frequency of A

F(E) = Frequency of all other outcomes

Rules

Max probability of an outcome is 1.0

oAll probabilities must add up to 1

Addition rule:

oUsed when finding probability of single independent events

P (A or B) = P(A) + P(B)

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