The Bottom Line: Violent crime on O‘ahu is currently: slightly up in several categories, but stable or lower in others.
We apologize that our October and November reports are late; it’s been a busy time in the semester!
Each month, we analyze the crime data provided publicly by the Honolulu Police Department to understand crime trends and put the headlines in perspective. Currently, for each category of violent crime, we compare the number of crimes last month to the month before and the same month in the previous year. (Note that our numbers for September have changed slightly reflecting changes in the HPD Dashboard, which updates the numbers as new information is added to their system.) We do a simple statistical analysis to determine whether the year-over-year or month-to-month variation is out of the norm or expected variation. In future posts, we will offer more long-term analyses using more data. For now, our goal is a quick assessment.
If this is your first visit to the Crime Lab, check out our primer on understanding crime rates.
Aggravated Assault
There were 106 aggravated assaults in October. This is up slightly from October 2023 when there were 86. It is also up from the number in September when there were 72.
Is this change significant? Actually, yes. Both the year-over-year increase and the month-to-month increase are statistically significant.
Murder and Non-Negligent Homicide
There were 2 homicides in October. This is up slightly from October 2023 when there was 1. It is the same as the number in September when there were 2.
Is this change significant? No. Neither the year-over-year drop nor the month-to-month stability are statistically significant, meaning they are within expected variation.
Robbery
There were 73 robberies in October. This is up from October 2023 when there were 51. It is also up from the number in September when there were 38.
Is this change significant? Actually, yes. Both the year-over-year increase and the month-to-month increase are statistically significant.
Sexual Assault
There were 70 sexual assaults in October. This is down from October 2023 when there were 93. It is up slightly from the number in September when there were 65.
Is this change significant? Actually, yes, some of them. The year-over-year drop is statistically significant; but the month-to-month increase is not.
Looking Back and Looking Forward
Last month, some of the variation in the counts of violent crime (except homicide) were significantly lower than either the previous month, the same month the previous year, or both.
This month, we’re seeing that, again, some significant changes. Two of the violent crime categories (aggravated assault and robbery) are significantly up. Homicide numbers are about the same, and sexual offenses are significant lower.
Once again, seeing this short-term variation is a good reminder that the crime rate is highly stochastic, meaning it fluctuates quite a lot and we really have to look at the trend over time. So far, the numbers have been fluctuating, with no clear trend.
Next Steps
We are in the process of compiling data to construct graphs to show what the trends look over time like instead of providing snapshots. One snag is because the reported crime data change each month as new information comes to light, we need to either update the numbers or be okay with the counts being off by 1-5. We are leaning toward accepting the inherent variability of the data instead of re-entering the data for all the months included in the analysis on a monthly basis. We also hope to continue to pull back the curtain and discuss how we calculate the expected variation. For now, we hope our analysis provides some context.
Additionally, keep an eye out for another special look at crime in West O‘ahu as a followup to our last post putting the crime trends in statistical perspective.
Final Assessment
This month’s assessment is that violent crime on O‘ahu is slightly up in several categories, but stable or lower in others. But remember: fluctuations are to be expected and we really want to look at trends, so a future post will offer that look!
The Hawaii Crime Lab 