Introduction to Probability

A variable is a characteristic that changes or varies over time, and/or for different individuals or objects under consideration. An experimental unit is the individual or object on which a variable is measured.

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Bar and pie charts are graphical techniques for qualitative data. The former focus the attention on the frequency of the occurrences of the categories, and the later emphasize the percentage of occurrences of each category.

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In a sample of 1000 students in a university, 125 of them or 12.5% are biology majors. The 12.5% is an example of statistical inference.

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Individual observations within each class may be found in a frequency distribution.

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Twenty-five percent of a sample of 200 professional tennis players indicated that their parents did not play tennis. This is an example of descriptive statistics as opposed to inferential statistics.

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A local cable system using a sample of 1000 subscribers estimates that fifty percent of its subscribers watch premium channel at least five times per week. This is an example of inferential statistics as opposed to descriptive statistics.

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Statistical inference is the process of making an estimate, prediction, or decision about a population based on sample data.

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In the term "frequency distribution," frequency refers to the number of data values or measurements falling within each class.

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A branch of the statistics discipline that is used to develop and utilize techniques for effectively presenting numerical information is called inferential statistics.

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A branch of the statistics discipline that is used to develop and utilize techniques for properly making inferences about population characteristics from information contained in a sample drawn from this population is called inferential statistics.

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