Chi-squared

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  • Created by: Sofalof
  • Created on: 24-04-15 18:01

Chi-squared

Advantages

  • Can test association between variables
  • Identifies differences between observed and expected values

Disadvantages

  • Can't use percentages
  • Data must be numerical
  • Categories of 2 are not good to compare
  • The number of observations must be 20+
  • The test becomes invalid if any of the expected values are below 5
  • Quite complicated to get right - difficult formula

Evaluation

Often used for spatial distribution. Can only be used for data in the form of frequencies in 2 or more groups/categories. The data must have a numerical value and the total observations must exceed 20 and an expected frequency must exceed 5. Calculated value must be above the critical value to reject null hypothesis. 

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