. Author manuscript; available in PMC: 2018 Jul 1.

Published in final edited form as: Photochem Photobiol. 2017 Feb 22;93(4):1115–1122. doi: 10.1111/php.12719

Table 5.

Marginal and Multivariate Cox models (treating Fluence, PDT dose, and [¹O₂]_rx as continuous variables).

	DF	Estimated Coefficients			Adjusted R-square	Likelihood Ratio Tests

		Fluence	PDT dose	[¹O₂]_rx		Null	F	P	O	F + P	F + O	P + O
Marginal models
1. Fluence	1	0.0084			24.14%	20.33
p-value		<.0001				<.0001
2. PDT dose	1		0.0041		42.95%	41.26
p-value			<.0001			<.0001
3. 1O2	1			2.8788	49.19%	49.76
p-value				<.0001		<.0001
Multivariate models
4. F + P	2	0.0044	0.0033		47.12%	46.83	26.50	5.57
p-value		.0019	.0008			<.0001	<.0001	.0183
5. F + O	2	0.0001		2.8874	49.19%	49.76	29.43		<0.01
p-value		.9824		<.0001		<.0001	<.0001		0.9822
6. P + O	2		0.0015	2.2747	51.84%	53.68		12.42	3.92
p-value			.0805	<.0001		<.0001		.0004	.0477
7. F + P + O	3	0.0006	0.0015	2.1459	51.88%	53.75	33.42	12.49	3.99	6.92	3.99	0.07
p-value		.7936	.0798	.0056		<.0001	<.0001	.0019	.1360	.0085	.0458	.7913

DF: degree of freedom; Null: the null model with no factors; F: model 1, Fluence; P: model 2, PDT dose; O: model 3, [¹O₂]_rx; F + P: model 4, Fluence + PDT; F + O: model 5, Fluence + [¹O₂]_rx; P + O: model 6, PDT dose + [¹O₂]_rx; F + P + O: model 7, Fluence + PDT dose + [¹O₂]_rx. Likelihood ratio tests compare the multivariate models to the models with the same but fewer factors. A small p-value means the model with more factors is significantly better than the model with fewer factors.