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PLSC 751 - Probability and Relative Frequency
Suppose there are six faces on a dice. When we roll the
dice and the number on the top of the dice is 1, we define
this as a successful event. There are six different possible
outcomes. The probability of success is:
n/N = 1/6
Where n is the number of ways that are successful
outcomes and N is the total number of events.
Example:
The probability of drawing an ace from a deck of 52 playing
cards equals 4/52 = 1/13.
Definition:
The probability
of an event is the proportion of time that the event will
occur in the long run. Probability is the expected proportion
of successful events.
Definition:
The relative frequency
is the observed number of successful events for a finite
sample of trials. Relative frequency is the observed proportion
of successful events.
Example:
Suppose we toss a coin 50 times and have 27 heads and
23 tails. We define a head as a success. The relative
frequency of heads is:
n/N = 27/50 = 54%
The probability of a head is 50%. The
difference between the relative frequency of 54% and the
probability of 50% is due to small sample size.
Copyright
2000©, Ted Helms |
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