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Empirical probability

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A direct estimate could be found by counting the number of men who satisfy both conditions to give the empirical probability of the combined condition. An alternative estimate could be found by multiplying the proportion of men who are over 6 feet in height with the proportion of men who prefer
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For example, consider estimating the probability that the lowest of the daily-maximum temperatures at a site in February in any one year is less than zero degrees Celsius. A record of such temperatures in past years could be used to estimate this probability. A model-based alternative would be to
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A disadvantage in using empirical probabilities arises in estimating probabilities which are either very close to zero, or very close to one. In these cases very large sample sizes would be needed in order to estimate such probabilities to a good standard of relative accuracy. Here
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and fit it to the dataset containing past years′ values. The fitted distribution would provide an alternative estimate of the desired probability. This alternative method can provide an estimate of the probability even if all values in the record are greater than zero.
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can help, depending on the context, and in general one can hope that such models would provide improvements in accuracy compared to empirical probabilities, provided that the assumptions involved actually do hold.
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of the probability. If a trial yields more information, the empirical probability can be improved on by adopting further assumptions in the form of a
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is also used as an alternative to "empirical probability" or "relative frequency". The use of the phrase "a-posteriori" is reminiscent of terms in
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of a probability. In simple cases, where the result of a trial only determines whether or not the specified event has occurred, modelling using a
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An advantage of estimating probabilities using empirical probabilities is that this procedure is relatively free of assumptions.
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For example, consider estimating the probability among a population of men that they satisfy two conditions:
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strawberry jam to raspberry jam, but this estimate relies on the assumption that the two conditions are
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in which a specified event occurs to the total number of trials, i.e. by means not of a theoretical
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which represents an estimate of a probability not based on any observations, but based on
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Mood, A. M.; Graybill, F. A.; Boes, D. C. (1974). "Section 2.2".
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Mood, A. M.; Graybill, F. A.; Boes, D. C. (1974). "Section 2.3".
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might be appropriate and then the empirical estimate is the
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Ratio of the number of desired outcomes to total experiments
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for the same case if certain assumptions are made for the
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being the total number of outcomes of the experiment.
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Index

probability theory
statistics
event
outcomes
sample space
experiment
probability
experience
observation
frequency
empirical
estimator
estimate
binomial distribution
maximum likelihood estimate
Bayesian estimate
prior distribution
statistical model
feet
statistically independent
statistical models
probability distributions
Bayesian statistics
Bayesian inference
posterior probability
a priori probability
deductive reasoning
Empirical distribution function
Empirical measure
Estimating quantiles from a sample

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