Table 2. Effect of dichotomization on various effect size indices when true effect size d = −1.0.

	Dichotomization point (zyoung)
	2.5	−2	−1.5	−1.5	−0.5	0.0	0.5	1.0	1.5	2.0
pyoung	0.99	0.98	0.93	0.84	0.69	0.50	0.31	0.16	0.07	0.02
pold	0.93	0.84	0.69	0.50	0.31	0.16	0.07	0.02	0.01	0.00
nyoung passed	99	98	93	84	69	50	31	16	7	2
nold passed	93	84	69	50	31	16	7	2	1	0
nyoung failed	1	2	7	16	31	50	69	84	93	98
nold failed	7	16	31	50	69	84	93	98	99	100
pold-pyoung	−0.06	−0.14	−0.24	−0.34	−0.38	−0.34	−0.24	−0.14	−0.06	−0.02
dphi	−0.31	−0.50	−0.64	−0.77	−0.82	−0.77	−0.64	−0.50	−0.31	−0.20
dp	−0.31	−0.50	−0.64	−0.78	−0.82	−0.78	−0.64	−0.50	−0.31	−0.20
dhh	−1.11	−1.23	−0.98	−0.91	−0.88	−0.91	−0.98	−1.23	−1.11	-.–
dprobit	−0.85	−1.06	−0.98	−0.99	−0.99	−0.99	−0.98	−1.06	−0.85	-.–

Note. This example assumes that n per group is 100.