The committee noted the contrast between the June trough date for the majority of the monthly indicators and the October trough date for real personal income less transfers. There were two reasons for selecting the earlier date. The first was described above -- the fact that quarterly real GDP and GDI rose strongly in the fourth quarter. The second was that real GDI is a more comprehensive measure of income than real personal income less transfers, as it includes additional sources of income such as undistributed corporate profits. The committee's use of income-side measures, notably real GDI, is based on the accounting principle that the value of output equals the sum of the incomes that arise from producing the output. Apart from a random statistical discrepancy, real GDI satisfies that equality while real personal income does not.