Fourth National Incidence Study of Child Abuse and Neglect (NIS–4)

3.1.1 Overall Incidence of Harm Standard MaltreatmentTable 3–1 presents the estimates for Harm Standard maltreatment since theNIS–2. The shaded section gives the NIS–4 estimates. These represent annual estimatesfor 2005–2006, the period in which the NIS–4 data were collected. The right-hand sideof the table compares the NIS–4 findings with the estimates for the correspondingcategories from the earlier studies, the NIS–3 and the NIS–2. The NIS–3 estimates reflectthe incidence of maltreatment during 1993, and the NIS–2 estimates index the incidenceof maltreatment in 1986. The statistical significance of the comparison in question isindicated by an asterisk or letter(s), as the table footnotes explain.Table 3–1 shows that an estimated 1,256,600 children experienced HarmStandard maltreatment during the NIS–4 2005–2006 study year. This total reflects anincidence rate of 17.1 children per 1,000 children in the general population nationwide,which is equivalent to 1.71 children per 100, or to one child in every 58 in the UnitedStates. 25,26 The comparisons in the right-hand sections of the table indicate that the 2005–2006 annual incidence of all Harm Standard maltreatment is lower than thecorresponding estimate for 1993, a statistically marginal difference. 27 Specifically, therewas a 19% decrease in the total number of maltreated children since 1993. This decreasecorresponds to a 26% decline in the rate of overall Harm Standard maltreatment since theNIS–3. The rate measure conveys a child’s risk of experiencing the maltreatment, so onecan say that a child’s risk of suffering Harm Standard maltreatment was 26% lower in2005–2006 than it was in 1993. This decrease in incidence rate is statistically marginal,meaning that the estimated change closely approaches statistical significance but does notmeet the traditional statistical standard for concluding that the difference is not due tochance factors.25 The incidence rates in this chapter used the average of the July 2005 and July 2006 annual estimates asthe population denominator (U.S. Census Bureau, 2008a). This computation yielded the estimate that atotal of 73,635,000 children ages 0 through 17 were living in the United States during the NIS–4 2005–2006 study year.26 In this and subsequent chapters, all estimates concerning total numbers of children are rounded to thenearest hundred in order to avoid conveying a false sense of precision. All the estimates have associatedstandard errors which represent their degree of precision, given in Appendices B and C.27 Comparisons across studies use the rate measures (i.e., comparing the number of children maltreated per1,000) in order to take account of any changes in the size of the U.S. child population across the timeintervals. Appendix E gives the details of the between-study significance tests and their specific results.3–3