The inverse variance method for assessing measurements of dP/dt and equal-period spacings in rapid variable stars.

A technique which maximizes the inverse variance of the residuals of a model fit to observed data is described. Its use is illustrated to advantage in the detection and measurement of (i) equally spaced patterns of periods in the power spectra of pulsating white dwarfs, and (ii) changes in the oscillation period of rapid variable stars. Key words: methods: data analysis - stars: oscillations - stars: variables: other - white dwarfs.