Category: statistics

The Normal Distribution, the Z-Score and the Z-Table

The concept of the normal distribution is one of the key elements in the field of statistical research. Very often, the data we collect shows typical characteristics, so typical that the resulting distribution is simply called… “normal”. In this post, we will look at the characteristics of this distribution, as well as touch on some other concepts of notable importance such as:

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Mean, median or mode? Which measure of position to use (and when to get it wrong)

Measures of position, also known as position indices, or measures of central tendency, are values that summarize the position of a statistical distribution, providing a single figure that encapsulates the most important aspects of the data. In this brief discussion, we will explore some of the most common and practical indices, such as the various types of means, the median, quartiles, and percentiles.

Topics Covered
  1. Measures of Central Tendency
  2. Arithmetic Mean
  3. The Mean of Grouped Data
  4. The Weighted Mean
  5. The Geometric Mean
  6. The Harmonic Mean
  7. The Trimmed Mean
  8. The Median
  9. The Mode
  10. Relationship Between Mean, Median, and Mode
  11. Quartiles, Deciles, and Percentiles
  12. An Overview: The Very Useful 5 Numbers
  13. Let’s Help Ourselves with a Clever Graph: The Boxplot 
  14. A Practical SEO Case: Mean or Median for Sessions?
  15. Try It Yourself
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