4Describing_Data-latest

# 4Describing_Data-latest - Statistical Methods for Business...

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Slide #1 Statistical Methods for Business Decision-Making Describing Data

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Slide #2 Using Statistics at Work Raise your hands to answer How many ever (at any time) use statistics (numbers, charts, or graphs or analyses - correlations, regressions, etc.) on your job? Those who raised hands (see notes page) In what way(s) do you use statistics and for what purpose(s)?
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Slide #4
Slide #5 DESCRIBING DATA I. Introduction The data we collect when measuring a variable have different values . For example, the variable "revenue per month" probably will have different values each month: \$12,000,000; \$13,600,000; \$11,700,000; \$15,300,00 ; . . . . This group of different values is collectively referred to as the distribution of the variable.

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Slide #6 DESCRIBING DATA As a user of statistics, you'll want to be able to describe your variable's distribution. This is typically done by giving measures central tendency dispersion
Slide #7 DESCRIBING DATA Next, show how frequently each data value appears in the distribution. Shown with a table (a frequency distribution) or picture (a histogram.) Last, scattergrams (plots) sometimes reveal trends

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Slide #8 DESCRIBING DATA II. Central Tendency Measures of central tendency give us information about where the center of a distribution is located OR WHAT THE TYPICAL VALUE IS. There are three commonly used measures.
Slide #9 II. Central Tendency A. Mean How do you calculate the mean? This is the "average" of all the values in the distribution. add up all values in data and divide that sum by the number of data values. It is the most useful and frequently used measure. i x N

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Slide #10 II. Central Tendency B. Median What is the median? This is the value above and below which fall an equal number of values. It is the midpoint of the distribution . In other words, it locates the middle of data when they are arranged in increasing order .
Slide #11 II. Central Tendency - Median The steps to calculate the median are 1. arrange the data in increasing order 2. if you have an odd number of data values, the median is the middle data value 3. if you have an even number of data values, the median is the mean of the two middle values

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Slide #12 Exercise Find the median of the following data: 114, 426, 897, 36, 520, 0, 91, 44.
Slide #13 Solution Here n = 8 is even. Arranging the data in increasing order, we have 0, 36, 44, 91, 114, 426, 520, 897. 91 and 114 are the entries nearest the middle. Hence the median is (91 + 114) / 2 = 102.5

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Slide #14 II. Central Tendency C. Mode What is the mode? This is the value that occurs most frequently in the distribution. You can find variables with one mode several modes no mode or ala mode!
Slide #15 II. Central Tendency If I were to give you 200 values for a variable, which measures(s) of central tendency would you calculate?

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