[R] Need to calculate standard deviation by groups

Hello, please help me with this basic question, I already spent two days on the internet and textbooks trying to come up with an answer... I will simplify my question to an example, rather than base it on the original variable names. I have a Dataset with 4 variables, 2 cases. Variable A is a

[R] How to calculate confidence interval for each level of a binary explanatory variable when there is interaction

I have a logistic regression model with several categorical explanatory variables and one interaction term (between two binary variables, named A and B). I know how to calculate the odds ratios for the different levels of A and B (for A=1, e.g., I need to add the coeff for A to coeff for A*B, then