The daily latitude measurements of the International Polar Motion Service are analyzed. The annual oscillation in the data was modeled by separate oscillations in each observatory's latitude data. The separate oscillations varied in amplitude from 0.05\ to 0.15\ with standard deviations of about 0.007\. Within the resolation of the latitude residuals (⋅150 cm), there is no indication of the sharp changes which might be associated with earthquake effects. Then, applying Schuster's test to a periodogram of the residuals indicates that there are probably several processes occuring at amplitudes between 0.007\ and 0.03\ whose solution awaits a more precise measurement technique.