Dear Workshop Community, Our next meeting will be *Wednesday November 6*, where Nicole Pashley will present research on* "Causal Inference for Multiple Non-Randomized Treatment Using Fractional Factorial Designs"* *Abstract:* We explore a framework for addressing causal questions in an observational setting with multiple treatments. This setting involves attempting to approximate an experiment from observational data. With multiple treatments, this experiment would be a factorial design. However, certain treatment combinations may be so rare that, for some combinations, we have no measured outcomes in the observed data. We propose to conceptualize a hypothetical fractional factorial experiment instead of a full factorial experiment and lay out a framework for analysis in this setting. We also connect our design-based methods to standard regression methods. We illustrate the method and the challenges of this type of data through application. *Where:* CGIS Knafel Building, Room K354 (see this link <https://map.harvard.edu/?bld=04471&level=9> for directions). *When: *Wednesday, November 6 at 12 noon - 1:30 pm. All are welcome. Lunch will be provided. Best, Georgie