TABLE 3.

Comparison of children's hierarchical clustering solutions to adult's clustering solutions

Age Group	Practice sort		Same individual sort		Different individuals sort
	Adj. Rand (k = 3)	c	Adj. Rand (k = 3)	c	Adj. Rand (k = 3)	c
3‐year‐olds	0.21	−0.03	0.02	0	0.16	0.21
4‐year‐olds	1.0	0.86	0.14	0.2	0.14	0.2
5‐year‐olds	1.0	0.99	0.49	0.41	0.49	0.38
6‐year‐olds	1.0	0.98	0.83	0.65	0.38	0.40

Each value in the table represents the similarity between children's clustering at a specific age group and adults’ clustering solution. An adjusted Rand index of 0 indicates two clusters have a Rand index that matches the expected value for random groupings, with higher and lower values indicating higher‐ or lower‐than‐chance‐level similarity between the two clusters. c is the cophenetic correlation coefficient between the two dendrograms. This value ranges from −1 to 1 with values near 0 suggesting that the two dendrograms are not statistically similar. Additional measurements of similarity for all values of k are available in Section 6 of the Supporting Information.