Sites and sample sizes for the Ontario Incidence Study of Reported Child Abuse and Neglect (OIS) from 1993 to 2013
| OIS-1993 | OIS-1998 | OIS-2003 | OIS-2008 | OIS-2013 | |
| Site selection (sample/total) | 15/51 | 13/53 | 16/53 | 23/53 | 17/46 |
| Case selection | 1898 | 2193 | 4175 | 4415 | 3118 |
| Investigated children | 2447 | 3053 | 7172 | 7471 | 5265 |
| Provincial estimate of child maltreatment-related investigations | 46 683 | 64 658 | 1 28 108 | 1 28 748 | 1 25 281 |