"Anarchist historians enthusiastically report increases in production in the collectivized areas. According to Deidre Hogan, harvests had increased by up to five times. But the numbers vary widely. They have to be put into perspective of the significant regional differences, the inclusion of formerly uncultivated land, the statistical problems that will be discussed below, and most of all, the short time during that most of the collectives existed, none exceeding two years."