Table 1.

Significant discrepancy in the observed and expected frequencies of haemopoietic colonies exhibiting chromosomal instability defined by the incidence of nonclonal cytogenetic aberrations (7, 8)

α-Particle irradiation dose, Gy	Colonies exhibiting instability, n/n		Exact binomial test probability
	Observed	Expected Ps(>0)
0.25	2/5  =  0.400*	0.055	2.7  ×  10−3
0.5	6/12  =  0.500*	0.105	7.1  ×  10−4
0.5	16/26  =  0.615†	0.105	4.1  ×  10−10
0.5 combined data	22/38  =  0.579	0.105	1.2  ×  10−12
1.0	4/10  =  0.400*	0.200	0.12
1.0	41/64  =  0.640‡	0.200	1.5  ×  10−13
1.0 combined data	45/74  =  0.608	0.200	1.2  ×  10−13

Probabilities of obtaining the observed results if the expected values represent the true values was calculated by using an exact binomial test (10). 

^*From ref. 7. 

^†From ref. 8. 

^‡From the current study.