Statistical Measures

Ratios, Proportions, Rates

• Three kinds of frequency measures are used with two-category variables (also called dichotomous variables). These frequency measures are
• Ratios
• Proportions, and
• Rates.
• Before you learn about specific measures, it is important to understand the relationship between the three types of measures and how they differ. All three measures are based on the same formula:
  
        Ratio, proportion, rate = x/y x 10 ⁿ

• In this formula, x and y are the two quantities that are being compared.
• The formula shows that x is divided by y.
• 10 ⁿ is a constant that we use to transform the result of the division into a uniform quantity.
• The size of 10 ⁿ may equal 1, 10, 100, 1000 and so on depending on the value of n.
  Example:

  10² = 10 x 10 = 100
  10³ = 10 x 10 x 10 = 1000
  10⁵ = 10 x 10 x 10 x 10 x 10 = 100,000