by Dr Felicity Goodyear-Smith
The methodology of the study reported by Fanslow and Robinson (Violence against women in New Zealand: prevalence and health consequences, New Zealand Medical Journal, 2004, 117:1206) is sound. They used a rigorous randomly selected population-based cluster-sampling with interviews in Mandarin or Cantonese (2%) as well as in English. Their sample size was 2855 with an overall 66.9% response rate which is acceptable although not high. Elizabeth Robinson is a well-qualified biostatistician and the statistical analysis appears to be accurate.
My concern with the study is not how it was conducted but what was studied and how the results were reported. This was yet another study that looked only at intimate partner violence against women by male partners. Evidence indicates that men and women physically abuse their partners in similar percentages.  The Dunedin Multidisciplinary Health and Development longitudinal cohort study found that within partnerships, women actually used more physical violence than men.  This was both women reporting perpetrating more partner violence than men, and men reporting more victimisation than women.  However, far fewer defined this violence as ‘assault’ causing physical harm, and in those who did, more men than women were named as perpetrators. [4, 5] Findings suggest that about four men assault women for every one woman who assaults a man.
Partner homicide is a relatively rare event in New Zealand, with more women killed than men by their partners. A study of NZ homicides from 1978 to 1987 found that 82 men and nine women killed their partners during that decade.  Another NZ study of intentional murders between heterosexual intimates between 1988 to 1995 found 80 male and 22 female offenders.  These figures indicate an average of 11 women and three men murdered by their partners each year.
Fanslow & Robinson’s study found that 33% of ever-partnered Auckland women and 39% of Waikato women reported at least one act of physical violence by an intimate partner in their lifetime, and 15% and 17% respectively reported at least one lifetime act of physical violence by a non-partner. However only 5% of the Auckland women (5% CI 4-6.6) reported physical abuse in the past 12 months. The rate for Waikato women in the past 12 months was not in the table, but the 95% CI was 3.3 to 6.2, which suggests it was less than 5% for these women.
Some limitations of the study:
- The data come from retrospective self-reporting ie based on previous experienced acts of violence reported by the women and self-reported measures of ill health.
- Only women were interviewed when it is known that women initiate violence against men at least as often as men do against women, and a gender-neutral study interviewing both women and men would be of much greater value in understanding what is happening in NZ households between couples.
- The study was reported as one in three women experiencing physical abuse in their lifetime. However only about 5% had experienced this in the past 12 months. While not condoning any physical violence, women who may have had a slap from a boyfriend in their youth but who are now happily married need to be differentiated from women who are currently at risk of being victims of partner violence. In fact most women at not at risk of being beaten by their partners but a small group are at high risk. A 1996 NZ victimisation study surveyed a random sample of 5000 people over the age of fifteen.  One of the most striking results reported was that most people have little exposure to violence or threats, but there is a small percentage of the population for whom violent events are nearly commonplace. Only 0.5% of the sample (6% of those who had been victimised) had been victims of a violent offence 5 or more times, but this group was subject to a 68% of the overall violent offending. The average number of assaults in a year for these victims was twelve. Within the family, violence to a partner is often a chronic behaviour pattern, and those who do offend (both men and women) are likely to carry out repeated acts of violence within a one year period.
- Physical violence included having ever been slapped; had something thrown at them that could have hurt them; been pushed; shoved or had their hair pulled (classified as moderate violence) or been kicked, dragged, beaten up, choked on purpose, threatened with a weapon or had a weapon used on them (severe violence). Moderate violence could therefore include having something thrown towards them eg a book that was not aimed at hitting them (and did not hit them) once in their life.
- Goodyear-Smith F, Laidlaw T. (1999) Aggressive acts and assaults in intimate relationships: Towards an understanding of the literature. Behavioral Sciences & the Law;17:285-304.
- Magdol L, Moffitt T, Caspi A, Newman D, Fagan J, Silva P. (1997) Gender differences in partner violence in a birth cohort of 21-year-olds: bridging the gap between clinical and epidemiological approaches. Journal of Consulting & Clinical Psychology;65:68-78.
- Moffitt TE, Caspi A, Krueger RF, Magdol L, Margolin G, Silva PA, Sydney R. (1997) Do partners agree about abuse in their relationship?: A psychometric evaluation of interpartner agreement. Psychological Assessment;9:47-56.
- Martin J, Nada-Raja S, Langley J, Feehan M, McGee R, Clarke J, Bedd D, Hutchinson-Cervantes M, Moffitt T, Rivara F. (1998) Physical assault in New Zealand: the experience of 21 year old men and women in a community sample. New Zealand Medical Journal;111:158-160.
- Langley J, Martin J, Nada-Raja S. (1997) Physical assault among 21-year-olds by partners. Journal of Interpersonal Violence;12:675-684.
- Fanslow JL, Chalmers DJ, Langley JD. (1995) Homicide in New Zealand: an increasing public health problem. Australian Journal of Public Health;19:50-57.
- Anderson T. Murder between sexual intimates in New Zealand 1988-1995. Wellington: Victoria University of Wellington; 1997.
- Young W. (1997) Crime in New Zealand. New Zealand Law Journal:343-345.