Validation of IHAD

Once the index was calculated, it was checked to ensure that it measured the desired concept and that the results make intuitive sense. This validation is important to establish the credibility of the index and identify any issues that may have been missed in the construction of the index. 

A range of validation checks were applied to the 2021 IHAD, including:

• comparison with the experimental IHAD 2016,
• comparison with 2021 SEIFA IRSAD, 
• sense checking of the SA1s with the highest and lowest proportions in quartile 1 or quartile 4, and 
• sense checking of SA1s where SEIFA IRSAD and IHAD differed the most. 

Results showed that IHAD 2021 is consistent with both the 2021 SEIFA IRSAD and the experimental IHAD 2016. The top and bottom SA1s were sensible and SA1s where IRSAD and IHAD differed the most were reasonable.  These checks confirmed that IHAD was performing as intended, in adding value to SEIFA IRSAD by showing the distribution of advantage and disadvantage at household level.