Method for determining the root mean square value of a vibration variable that is measured on a machine , wherein: a test measurement is carried out in order to obtain a test signal of the vibration variable with a test signal length, wherein the test signal length is at least twice as long as the period duration of the lowest beat frequency; the influence of the shortening of the signal length of the test signal on the associated root mean square value is estimated and the relative deviation of the root mean square value emerging for a shortened signal length from the root mean square value emerging for the full test signal length is estimated therefrom as a function of the signal length in order to obtain a root mean square value error function, wherein the test signal is squared and transformed into the frequency domain in order to obtain spectral components of the squared test signal, wherein the influence of the shortening of the signal length of the test signal on the spectral components by windowing the test signal is estimated in order to estimate the influence of the shortening of the signal length of the test signal on the emerging root mean square value, and the influence of the shortening of the signal length of the test signal on the root mean square value is estimated by virtue of ascertaining a weighted sum of spectral components, with the weighting depending on the signal length; and a measurement of the vibration variable is carried out for the purposes of determining the root mean square value, wherein the measurement duration of this measurement is selected on the basis of the root mean square value error function. a test measurement is carried out in order to obtain a test signal of the vibration variable with a test signal length, wherein the test signal length is at least twice as long as the period duration of the lowest beat frequency; the influence of the shortening of the signal length of the test signal on the associated root mean square value is estimated and the relative deviation of the root mean square value emerging for a shortened signal length from the root mean square value emerging for the full test signal length is estimated therefrom as a function of the signal length in order to obtain a root mean square value error function, wherein the test signal is squared and transformed into the frequency domain in order to obtain spectral components of the squared test signal, wherein the influence of the shortening of the signal length of the test signal on the spectral components by windowing the test signal is estimated in order to estimate the influence of the shortening of the signal length of the test signal on the emerging root mean square value, and the influence of the shortening of the signal length of the test signal on the root mean square value is estimated by virtue of ascertaining a weighted sum of spectral components, with the weighting depending on the signal length; and a measurement of the vibration variable is carried out for the purposes of determining the root mean square value, wherein the measurement duration of this measurement is selected on the basis of the root mean square value error function. <EOS>