1. Barriers to diaphragm use: the views of advanced practice nurses;Kulczycki, A.; Qu, H.; Bosarge, P.M.; Shewchuk, R.M.;J Fam Plann Reprod Health Care,2010
2. Practical Statistics for Medical Research;Altman, D.G.,1999
3. Testing and quantifying association in binary data;Warner, P.;J Fam Plann Reprod Health Care,2009
4. Categorical variable Chi-square test Confidence interval (CI) (95%) Correlation coefficient Degrees of freedom (df)
5. Null hypothesis (NH) Ordinal association Ordinal variable