To ensure that your results are valid, consider the following guidelines when you collect data, perform the analysis, and interpret your results.
- The data should be continuous or ordinal
- If you have categorical data, you should perform Cross Tabulation and Chi-Square to examine the association between variables.
- The relationship between variables should be linear or monotonic
- If your variables do not have a linear or monotonic relationship, the results from the correlation analysis will not accurately reflect the strength of the relationship. To check for other forms of relationships, use Scatterplot or Fitted Line Plot.
- Unusual values can have a strong effect on the results
- Because unusual values can have a strong effect on the results, use Scatterplot or Fitted Line Plot to identify these values. You should investigate outliers because they can provide useful information about your data or process.