Table 3.

The coefficients of association between age and citation number/density, across various levels of evidence

	Citations~Age				Density~Age
Level of evidence	Pearson	P-Value	Kendall	P-Value	Pearson	P-Value	Kendall	P-Value
I	0.456	0.4402	0.105	0.8005	0.266	0.6658	0.111	0.7947
II	0.391	0.005	0.0833	0.4053	-0.540	<0.001	-0.557	<0.001
III	0.494	0.2594	0.488	0.1287	-0.887	0.0078	-0.586	0.0683
IV	0.249	0.4872	-0.0227	0.9282	-0.700	0.0241	-0.796	0.0016
V	-0.235	0.228	0.0267	0.8432	-0.540	0.003	-0.709	0.0<0.001