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• A random variable is an assignment of numbers to the outcome of some random (or partially random) event.
• A characteristic that takes on certain values in a random manner is called a random variable.
• A sampling distribution is a collection of all the means from all possible samples of the same size taken from a population.
• In a sampling distribution, each of the observations in the distribution must consist of a statistic that describes a collection of data points.
• A sampling distribution is a set of all possible values in a population, except the values themselves represent statistics, like sample means or sample standard deviations. The critical element in each case is that data points going into your distribution each represent a summary statistic for a sample.

  The Experts at For Dummies. Statistics: 1001 Practice Problems For Dummies (+ Free Online Practice) (p. 256). Wiley. Kindle Edition.
• A sampling distribution is a population of data points where each data point represents a summary statistic from one sample of individuals.

  The Experts at For Dummies. Statistics: 1001 Practice Problems For Dummies (+ Free Online Practice) (p. 256). Wiley. Kindle Edition.
• A population distribution is a population of data points where each data point represents an individual.

  The Experts at For Dummies. Statistics: 1001 Practice Problems For Dummies (+ Free Online Practice) (p. 256). Wiley. Kindle Edition.
• standard of error of a sample mean is ox=ox/square root of n
• The standard deviation represents the variability in the entire population, or the variability of X.

  The Experts at For Dummies. Statistics: 1001 Practice Problems For Dummies (+ Free Online Practice) (p. 257). Wiley. Kindle Edition.
• The standard error represents the variability of the sample means, or the variability of .

  The Experts at For Dummies. Statistics: 1001 Practice Problems For Dummies (+ Free Online Practice) (p. 257). Wiley. Kindle Edition.
• A smaller standard error will give you a more precise estimate of the mean because the sample means will cluster more closely around the population mean.

  The Experts at For Dummies. Statistics: 1001 Practice Problems For Dummies (+ Free Online Practice) (p. 262). Wiley. Kindle Edition.
• Units for standard error are the same as for the original measurements.

  The Experts at For Dummies. Statistics: 1001 Practice Problems For Dummies (+ Free Online Practice) (p. 262). Wiley. Kindle Edition.
• When samples are drawn from a normally distributed population, the sampling distribution of sample means is normal.

  The Experts at For Dummies. Statistics: 1001 Practice Problems For Dummies (+ Free Online Practice) (p. 263). Wiley. Kindle Edition.