Source Type III SS degrees of freedom Mean Squares F-ratio P-value Time 203.53 1 203.53 39.0 <0.0001 Season 586.81 3 195.60 37.5 <0.0001 Farm 65.43 2 32.72 6.3 0.002 Time*Season£ 303.67 3 101.22 19.4 <0.0001 Season*Farm€ 524.50 6 87.42 16.7 <0.0001 Error 1410.24 270 5.22     £ Interaction - effect of each increase in 1 hr of time since pasteurization within each season; see Table 1 for estimated effects € Interaction – effect of season on a specific farm; see Table 1 for estimated effects R2=0.71, P<0.0001

Table 2: General linear model tests of significance for effects on log of bacteria count (LogSPC in cfu/ml) in milk following pasteurization (see Table 1 for explanation of Time, Season and Farm).