High Quality Content by WIKIPEDIA articles! RATS, an abbreviation of Regression Analysis of Time Series, is a statistical package for time series analysis and econometrics. It is fully featured package and at the same is inexpensive as compared to similar commercial alternatives. RATS is owned by Estima, Inc., located in Evanston, IL. The forerunner of RATS was a FORTRAN program called SPECTRE, written by Christopher Sims, a professor of economics. SPECTRE was designed to overcome some limitations of existing software that affected Sims' research in the 1970s, by providing spectral analysis and also the ability to run long unrestricted distributed lags. The program was then expanded by Tom Doan, then of the Federal Reserve Bank of Minneapolis, who went on to found the consulting firm that owns and distributes RATS software.