Correlation Analysis (Spearman rho) - FAQ?

Correlation is a bivariate analysis that measures the strength of association between two variables and the direction of the relationship.

In terms of the strength of relationship, the value of the correlation coefficient (rs) varies between+1 and -1. As the correlation coefficient value goes towards 0, the relationship between the two variables will be weaker.

The direction of the relationship is indicated by the sign of the coefficient; a + sign indicates a Direct relationship and a – sign indicates a Inverse relationship.

    In general,
  • rs > 0 implies positive agreement among ranks
  • rs < 0 implies negative agreement (or agreement in the reverse direction)
  • rs = 0 implies no agreement
Spearman rank correlation: It is a non-parametric test that is used to measure the degree of association between two variables. The Spearman rank correlation test does not carry any assumptions about the distribution of the data.

The following formula is used to calculate the Spearman rank correlation:

Survey Software Help Image
  • rs = Spearman rank correlation
  • D = the difference between the ranks of corresponding variables
  • n = number of observations

How can I run correlation analysis for my survey?

Go to: My Surveys » Select Survey » Analytics

Click on Correlation Analysis under the Analysis drop down.

Survey Software Help Image
    By default, we display 2*2 matrix which shows the corelation coeffecient of first 2 questions of the survey. To Correlate other questions:
  • Select the questions in Rows and columns that you wish to correlate. You can also select all questions.
  • Click on Recalculate correlation coeffecient button to generate the report.
Survey Software Help Image

Threshold section help user with the color coding of the cells which indicates the strength of the relationship between the variables. Direct correlation will have deafult set threshold to 0.65 and has 3 colors. If correlation coeffecient value is below 0.80 to 0.65(set threshold) cell will be colored with light green indicating low strength of relationship. If the value is between 0.80 to 0.90 cell is colored with medium green and if value is above 0.90 cell is colored with dark green indicating high strength of correlation between 2 variables.

Survey Software Help Image

In the above example, we find out the relationship between age and highest qualification, highest qualification and household income, age and household income is positive and color coded according to the strength of the relationship.

This implies there is very strong association between the variables. Any increase in one variable leads to increase in other.

When user enables inverse correlation, Cells with inverse relation gets highlighted. We have similar buckets in inverse correlation. If correlation coeffecient value is below -0.80 to -0.65(set threshold) cell will be colored with light red indicating low strength of relationship. If the value is between -0.80 to -0.90 cell is colored with medium red and if value is above -0.90 cell is colored with dark red indicating high strength of correlation between 2 variables.

Survey Software Help Image

In the above example, we find out the relationship between age and gender, gender and highest qualification is negative and is color coded according to the strength of the relationship.

Excel download with color coding of the cells is supported for the correlation analysis.

What question types are supported for Correlation Analysis?

All multi choice questions are supported for correlation analysis.

License

This feature/tools described here are available with the following license(s) :

Corporate Edition and above

Was this article helpful?
Sorry about that
How can we improve it?
Submit