Finding z-scores & using z-tables

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What is a z-score?

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A z-score is a statistical measurement that describes a value's relationship to the mean of a group of values, expressed in terms of standard deviations from the mean.

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How do you calculate a z-score?

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The formula for calculating a z-score is: z = (X - μ) / σ, where X is the value, μ is the mean, and σ is the standard deviation.

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What does a negative z-score indicate?

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A negative z-score indicates that the value is below the mean of the data set.

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What does a positive z-score indicate?

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A positive z-score indicates that the value is above the mean of the data set.

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What is the mean in a data set?

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The mean is the average of all the values in a data set, calculated by summing all values and dividing by the number of values.

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What is the standard deviation?

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Standard deviation is a measure of the amount of variation or dispersion in a set of values.

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How do you interpret a z-score of 0?

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A z-score of 0 indicates that the value is exactly equal to the mean of the data set.

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What is a z-table?

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A z-table is a table that shows the percentage of values below a given z-score in a standard normal distribution.

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How can you use a z-table to find the percentage of scores below a certain z-score?

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To find the percentage of scores below a certain z-score, locate the z-score in the z-table, which will provide the cumulative probability corresponding to that z-score.

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What percent of scores are below a z-score of -1?

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Approximately 15.87% of scores are below a z-score of -1.