A Comparative Study of Palatal Rugae Patterns among Igbo and Ikwerre Ethnic Groups of Nigeria: A University of Port Harcourt Study

Table 2

-test of proportionality difference in rugae pattern distribution between Ikwerre and Igbo females.

Pattern	Tribe	Obs. population ()	Sampled population ()	Obs. proportion	-value (calculated)	critical	value (obs.)	Inference
Wavy	Ikwerre	117	289	0.405	−4.7572	1.96	<0.0001	Significant difference in proportions *
	Igbo	188	314	0.599
Curvy	Ikwerre	99	289	0.343	2.1791	1.96	0.02926	Significant difference in proportions *
	Igbo	82	314	0.261
Circular	Ikwerre	14	289	0.048	−0.9672	1.96	0.33204	No significant difference in proportions
	Igbo	21	314	0.067
Straight	Ikwerre	34	289	0.118	3.1373	1.96	0.00168	Significant difference in proportions *
	Igbo	15	314	0.048
Converging	Ikwerre	7	289	0.024	0.7289	1.96	0.4654	No significant difference in proportions
	Igbo	5	314	0.016
Diverging	Ikwerre	18	289	0.062	3.5282	1.96	0.00042	Significant difference in proportions *
	Igbo	3	314	0.01

The asterisks were used to demonstrate values with significant difference.