Table 2

Case and control playground measurements

Measurement	Cases			Controls			Test statistic
Measurement	n	Mean	SD	n	Mean	SD	Test statistic
*p⩽0.05.
Equipment height (m)	371	2.04	0.43	279	1.97	0.52	t = 1.96, p = 0.05*
Fall height (m)	371	1.52	0.37	279	1.42	0.41	t = 3.10, p<0.01*
Surface depth (mm)	361	111	50	271	104	51	t = 1.73, p = 0.08
Arm load (kN)	369	5.30	1.91	276	5.23	1.68	t = 0.47, p = 0.64
G_1m	339	82.87	38.83	265	78.76	27.19	t = 1.47, p = 0.14
G_CoG	276	102.29	43.96	260	94.38	37.43	t = 2.24, p = 0.03*
G_equipment	198	118.45	46.42	229	111.98	42.56	t = 1.50, p = 0.13
HIC_1m	339	241.23	185.55	265	230.02	161.00	t = 0.78, p = 0.44
HIC_CoG	276	439.43	398.70	260	371.08	265.62	t = 2.31, p = 0.02*
HIC_equipment	198	615.04	450.75	229	553.95	365.61	t = 1.54, p = 0.13