. Author manuscript; available in PMC: 2019 Jun 27.

Published in final edited form as: Int Arch Occup Environ Health. 2014 Sep 13;88(4):477–484. doi: 10.1007/s00420-014-0977-y

Table 2.

Comparisons for Licensed Practical Nurses

	Average injury rate¹		Difference (“Before” -“After” Law)	95% confidence interval for the difference
	Before law	After law		Lower bound	Upper bound
Comparison #1; average injury rate 00–03 vs. 05–08
California	244.27	90.27	154.01	80.397	227.623
USA - California	167.86	107.07	60.78	44.058	77.502
Difference-in-difference (percent reduction from California “before” law)			93.23 (33.6%)
Comparison #2; average injury rate 01–03 vs. 05–07
California	209.18	97.00	112.17	39.908	184.432
USA - California	164.64	112.93	51.71	34.894	68.529
Difference-in-difference (percent reduction from California “before” law)			60.47 (28.9%)
Comparison #3; average injury rate 99–03 vs. 05–09
California	229.95	90.67	139.28	67.213	211.347
USA - California	171.00	103.67	68.33	51.509	85.151
Difference-in-difference (percent reduction from California “before “law)			70.95 (30.9%)

Average injury rates were calculated per 10,000 licensed practical nurses per year.