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QBA 260

QBA 260. Chapter 4. Measures of Central Tendency. Statisticians use measures of central tendency as a way of describing data Three common measures of central tendency are: Mean (Average) Median – the middle value in the dataset Mode – the value that occurs most frequently in the dataset.

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QBA 260

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  1. QBA 260 Chapter 4

  2. Measures of Central Tendency • Statisticians use measures of central tendency as a way of describing data • Three common measures of central tendency are: • Mean (Average) • Median – the middle value in the dataset • Mode – the value that occurs most frequently in the dataset

  3. Calculating an Average • The data are represented by • x1, x2, x3,…, xn • The average is the sum of the data values divided by the number of data values

  4. Calculating an Average • Data: 12, 14, 9, 12, 8 • Sum: 12 + 14 + 9 + 12 + 8 = 55 • n: 5

  5. Excel Functions • AVERAGE • Uses only numbers • AVERAGEA • Treats text as zeroes unless the text is TRUE • TRIMMEAN • Eliminates the most extreme values before calculating the average

  6. Trimmed Average • Deletes the most extreme lower and upper values • 40% trimmed • 1, 2, 3, 4, 5 • 1, 2, 30, 4, 5 • 1, 2, 300, 4, 5

  7. The Median • The median is the value in the middle when the data are ordered • 10, 12, 15, 18, 21, 34, 88 • 10, 12, 15, 18, 21, 34

  8. The Mode • The mode is the most common value • 1, 2, 3, 2, 4, 6, 2, 3, 1, 5, 4

  9. Scales of Measurement • Average • Interval or ratio data • Median • Ordinal, interval or ratio data • Mode • Nominal, ordinal, interval, or ratio data

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