Table 2.

Interrater reliability: Level of agreement between plate waste assessed by two raters in using the visual quarter-waste method for foods from 59 trays in 3 middle school and high school cafeterias in one Washington State school district during May 2014

Food or beverage item	n	κa	Standard errorbc
Food
Cheese pizza	11	1.0	0.302
Fries with entree	9	1.0	0.270
Hot dog	6	1.0	0.320
Baby carrots	5	1.0	0.338
Seafood basket	5	1.0	0.374
Sub sandwich	9	0.91	0.249
Canadian bacon and pineapple pizza	5	0.89	0.237
Side fries	13	0.69	0.233
Pepperoni pizza	7	0.59	0.344
Beverage
White milk	12	1.0	0.237
Chocolate milk	31	0.87	0.137
Orange juice	6	0.81	0.281
Apple juice	33	0.78	0.128

^aMeasures the amount by which the agreement between two ratings exceeds that expected by chance. κ=1 when agreement is perfect and κ=0 when agreement is no better than chance.

^bFor small numbers of pairs (<30) there is reduced confidence in the reliability of these standard errors.

^cBecause trays were randomly distributed to members of the research team, these standard errors do not account for differences between raters.