Measures of Central Location

The Mean

Learning Outcomes

Understand and calculate means (averages) both by hand and in Excel.

  • The sum of the numbers divided by the number of numbers.
  • Also called the ‘Arithmetic Mean’ or Average
  • The formula is: [latex]\bar{x} = \frac{\sum_{i=1}^{n} X_i }{n}[/latex]

Understanding Summation Notation (Σ)

  • Σ means the summation (to add up all of the x terms).
  • It is often used in Statistics
  • Many metrics require us to sum up the values or squared values of a data set
  • And it is quicker to use the ‘summation notation’ to express that sum.

EXAMPLE 1.1 — USING SUMMATION NOTATION

If the data set ‘X’ contains the following data:

x= 55, x= 62, x= 67, x= 60, x= 71, x= 66

then:

Σ xi = x1 + x2 + x3 + x4 + x5 + x6

= 55 + 62 + 67 + 60 + 71 + 66

= 381

Calculating Mean Values by Hand (Exercise)

To calculate an average (mean), we simply do the following:

  1. Sum up all of the values (Σ xi)
  2. Count the number of values in the data set (n)
  3. Divide the sum of all the terms by the number of data in the data set (Σ xi / n)

Knowledge Check 1.1.2

Try the following exercise below to practice what you’ve learned:
Conclusion: The average income per resident is roughly $63,500.

Calculating the MEAN USing Excel (Video)

We will use the average call in Excel:

  • Type: ‘ = average()’
  • Select all of the elements across the row or column you would like to average
  • Hit enter

EXAMPLE 1.2 — USING EXCEL TO FIND AN AVERAGE

Sample vs population Notation

Populations

  • A population is the entire group that you want to draw conclusions about
  • The population mean is indicated by the symbol μ (mu)
  • Ex: All students currently registered in the BCIT School of Business make up the population

Samples

  • A sample is the specific group that you will collect data from that will not include all members of the population
  • The sample mean is indicated by the symbol x̄ (x-bar)
  • Ex: A randomly selected group of students from BCIT whose last name begins with the letter ”B”.

Key Takeaways (exercise)

Key Takeaways: The Mean

Your Own Notes

  • Are there any notes you want to take from this section? Is there anything you’d like to copy and paste below?
  • These notes are for you only (they will not be stored anywhere)
  • Make sure to download them at the end to use as a reference

License

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An Introduction to Business Statistics for Analytics (1st Edition) Copyright © 2024 by Amy Goldlist; Charles Chan; Leslie Major; Michael Johnson is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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