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. 2011 May 17;12:99. doi: 10.1186/1471-2474-12-99

Table 2.

Spline regression parameters of the final 4 clusters

Cluster 1,
n = 43,
mean
Cluster 2,
n = 23,
mean
Cluster 3,
n = 72,
mean
Cluster 4,
n = 27,
mean
Intercept,
First
regression
1.45 9.44 5.76 5.07
Slope,
First regression
0.06 -3.08 -1.06 -0.26
Slope,
Second regression1
-0.02 -0.03 -0.02 -0.09
Intersection between first and second regression,
"knot"2
4.84 2.77 4.40 12.04

1 The parameter used for the cluster analysis was actually the difference in slopes between the first and second regressions. To facilitate the interpretation, we show the parameter here as the slope of the second regression.

2 This parameter is scaled in weeks.