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7 Cards in this Set
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discrete random variable
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A is one which may take on only a countable number of distinct values such as 0,1,2,3,4,........ Discrete random variables are usually (but not necessarily) counts. If a random variable can take only a finite number of distinct values, then it must be discrete. Examples of discrete random variables include the number of children in a family, the Friday night attendance at a cinema, the number of patients in a doctor's surgery, the number of defective light bulbs in a box of ten.
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continuous random variable
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s a random variable where the data can take infinitely many values
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probability distribution
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a function of a discrete variable whose integral over any interval is the probability that the random variable specified by it will lie within that interval.
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Variance of s random sample
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expected value of the square of the difference between the random variable and the mean.
Given that the random variable X has a mean of μ, then the variance is expressed as: |
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random variable
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The outcome of an experiment need not be a number, for example, the outcome when a coin is tossed can be 'heads' or 'tails'. However, we often want to represent outcomes as numbers. A random variable is a function that associates a unique numerical value with every outcome of an experiment. The value of the random variable will vary from trial to trial as the experiment is repeated.
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mean of the random variable
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a quantity having a numerical value for each member of a group, especially one whose values occur according to a frequency distribution.
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standard deviations of random samples
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For a discrete random variable the standard deviation is calculated by summing the product of the square of the difference between the value of the random variable and the expected value, and the associated probability of the value of the random variable, taken over all of the values of the random variable, and finally taking the square root.
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