M.F.O. (Max Felix Orson) Welz

Max Felix Orson Welz
Erasmus School of Economics (ESE)
Erasmus University Rotterdam
ERIM PhD Candidate
Field: Marketing
Affiliated since 2020

PhD Track Robustifying the Analysis of Big Rating-Scale Data Against Outliers

Due to modern technology and the internet, data collection is nowadays easier than ever. Consequently, datasets are growing ever larger, both in terms of sample size and dimension. On the other hand, large datasets are more likely contain potentially harmful outliers that are in turn difficult to detect given the dimension of the data. The issue of detecting outliers exacerbates when the data is noncontinuous, such as rating-scale data. However, statistical literature on outliers in rating-scale data is scarce.

In this PhD track, we will (i) develop methods for identifying outliers in (potentially large) rating-scale datasets; (ii) develop fast and efficient statistical estimation methods that are robust to outliers in high-dimensional data, in particular in rating-scale-data; (iii) derive mathematical guarantees such as convergence properties and asymptotic theories for the developed methods. The overall goal of this PhD track is to contribute to the scarce literature on robustness in noncontinuous data. The methods that we will develop are attractive for social scientists and researchers/practitioners that work with rating-scale data, as our proposed methods will make their analyses more reliable and less prone to the adverse effects of outliers.

Robust statistics, rating scales, sparsity, regularized regression, machine learning, big data, singular value decomposition, asymptotic theory
Time frame
2020 -


  • Academic (5)
    • Alfons, A., & Welz, M. (2024). Open Science Perspectives on Machine Learning for the Identification of Careless Responding: A New Hope or Phantom Menace? Social and Personality Psychology Compass, 18(2), Article e12941. https://doi.org/10.1111/spc3.12941

    • Franses, P. H., & Welz, M. (2022). Evaluating Heterogeneous Forecasts for Vintages of Macroeconomic Variables. Journal of Forecasting, 41(4), 829-839. https://doi.org/10.1002/for.2835

    • Franses, P. H., & Welz, M. (2022). Forecasting Real GDP Growth for Africa. Econometrics, 10(1), Article 3. https://doi.org/10.3390/econometrics10010003

    • Franses, P. H., & Welz, M. (2020). Does More Expert Adjustment Associate with Less Accurate Professional Forecasts? Journal of Risk and Financial Management, 13(3), 1-7. Article 44. https://doi.org/10.3390/jrfm13030044

    • Franses, P. H., & Welz, M. (2020). The Cash Use of the Malaysian Ringgit: Can it Be More Efficient? Annals of Financial Economics, 15(1), 1-5. https://doi.org/10.1142/S2010495220500049


Visiting address

Burgemeester Oudlaan 50
3062 PA Rotterdam

Postal address

Postbus 1738
3000 DR Rotterdam