TABLE 2.

Multiple linear regression analysis^a results for the effects of contact time, inoculum matrix, food type, and surface type and their interactions on the transfer of E. aerogenes from common household surfaces to foods

Variable or interaction	Coefficient	SE	LCLb	UCLc	t statistic	P value
Intercept	0.38	0.09	0.20	0.56	4.18	0.000030
Time	0.01	0.00	0.01	0.01	13.40	<0.000001
Matrix	−0.26	0.11	−0.47	−0.06	−2.49	0.012944
Food	0.23	0.04	0.15	0.32	5.36	<0.000001
Surface	−0.25	0.04	−0.33	−0.16	−5.78	<0.000001
Time × matrix	0.00	0.00	0.00	0.00	−0.68	0.494994
Time × food	0.00	0.00	0.00	0.00	−7.90	<0.000001
Time × surface	0.00	0.00	0.00	0.00	−3.11	0.001896
Matrix × food	−0.08	0.04	−0.17	0.00	−2.01	0.044589
Matrix × surface	−0.17	0.04	−0.25	−0.09	−4.06	0.000050
Food × surface	0.07	0.02	0.03	0.11	3.74	0.000190

^aQuantitative values were given to the following variables: surface (tile [0], stainless steel [1], wood [2], and carpet [3]), food (bread [0], bread with butter [1], gummy candy [2], and watermelon [3]), and inoculum matrix (TSB [0] and buffer [1]).

^bLCL, lower confidence limit.

^cUCL, upper confidence limit.