Table 3. Statistics describing the distribution of opening knowledge for each level of expertise.

Variable	Level of Expertise
	Class B	Class A	Candidate Masters	Masters
N	5,019	15,737	29,881	25,925
Elo (SE)	1721.29 (.78)	1915.11 (.45)	2103.21 (33)	2291.31 (.35)
Mean knowledge (SE)	14.26 (.10)	15.58 (.11)	16.71 (.12)	18.01 (.12)
95% CI upper bound	14.10	15.48	16.63	17.93
95% CI lower bound	14.42	15.68	16.78	18.10
Median	14.00	15.00	16.00	18.00
Variance	32.68	38.76	43.30	48.34
SD	5.72	6.23	6.58	6.95
Skewness	0.68	0.64	0.59	0.55
Kurtosis	0.86	0.58	0.47	0.27