A display apparatus includes: an operation input device configured to designate a data range of an observed value; an analysis condition setting device configured to determine an analysis range or an analysis parameter of the observed value, corresponding to the number of samples included in the data range; a computation device configured to analyze a waveform or a trend of the observed value on the basis of the analysis range or analysis parameter; and a display screen generation device configured to cause a display device to display a waveform or a straight line as a computation result of the computation device.