Methods, systems, apparatus and articles of manufacture to determine causal effects are disclosed herein. An example apparatus includes a weighting engine to calculate a first set of weights for a first set of covariates corresponding to a treatment dataset and a second set of weights for a second set of covariates corresponding to a control dataset using maximum entropy, the first set of weights to equal the second set of weights. The example apparatus also includes a weighting response engine to calculate a weighted response for the treatment dataset and a weighted response for the control dataset by: mapping the first set of weights and the second set of weights to a uniform weighting identifier, determining a constraint matrix based on the first set of weights, the second set of weights and the uniform weighting identifier, and bypassing multivariate reweighting by calculating the weighted response for the treatment dataset and the weighted response for the control dataset by applying maximum entropy to the constraint matrix.