The best replacement for covariates is factors.

The best alternatives to covariates are rated as following:
★★★★★  factors

Your alternative for covariates is not listed? Suggest!
Speaking about covariates, one probably shouldn't forget about repeated measures.

Other search terms related to covariates and their ratings are:
★★★★★ repeated measures
You have in mind a companion for covariates and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of covariates in all years. Click on graph for more.
covariates
factors