HB estimation is considered the "gold standard" for ACA part-worth utility estimation, exceeding the quality of the default OLS estimation. The benefits of HB estimation for ACA include:
1. Greater precision of estimates for each individual,
2. It relaxes the assumption of equidistant part-worths in the Priors for a priori ordered attributes,
3. Improved accuracy of part-worths for predicting holdout concepts,
4. It provides a theoretically more defensible approach for combining self-explicated and conjoint data.
We recommend that the interested user refer to the ACA/HB documentation (or the ACA/HB Technical Paper, available in our Technical Papers library at www.sawtoothsoftware.com) for more details about ACA/HB and its settings dialog.
Almost all of the capabilities of the standalone ACA/HB product are available within the Lighthouse Studio interface, except:
1. Ability to save draws
2. Unacceptable extrapolation
3. Ability to restart interrupted HB runs
4. Advanced output files are not written (.dra, .cov, .hbv, .log)
Output Files
When HB estimation is completed, the output is also displayed in a report window. The first (Summary) tab displays the average part-worth utilities across respondents (normalized by the zero-centered diffs method), and the average attribute importances. The second tab shows a summary of the settings. On the third (Individual Utilities) tab are the raw utility data for each respondent, organized as one row per respondent. Click the Save Report button to save the data as an Excel (.XLS) file.
Zero-Centered Diffs Method: The Summary tab displays the average rescaled utilities (as well as the standard deviations) under the zero-centered "diffs" method. The diffs method rescales utilities so that for each individual the total sum of the utility differences between the worst and best levels of each attribute across attributes is equal to the number of attributes times 100. This normalizes the data so that each respondent has equal impact when computing the population average.
When you run ACA/HB through the Lighthouse Studio interface, a studyname ACA.hbu file is also automatically generated in a subfolder of your study. The layout of this file is supplied in the ACA/HB manual.