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Show HN: Play with an interactive heatmap of SF crime (and other cities)

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Re: Show HN: Play with an interactive heatmap of SF crime (and other cities)

#51

Post by chatmasta »

mh- wrote: post #8
rachofsunshine wrote: post #6

Earlier quoted context omitted.

That's probably not the correct analysis, because the number you're trying to estimate is not P(a crime occurs near you), it's P(you will personally be the victim of a crime). Crime rate over density won't necessarily do that either (since the population density of a primarily commercial+touristy area, e.g. Fisherman's Wharf, is << the number of people who are present there on a given day), but neither does raw count…

I mean, I'd also be pretty interested in avoiding P(a crime occurs near you), especially as a tourist.

Yeah there are only 24 hours in a day, so the right metric might be density of crimes in an area per hour. Even if I’m not the victim of a robbery, I don’t really want to be watching it from across the street.

Re: Show HN: Play with an interactive heatmap of SF crime (and other cities)

#52

Post by binary132 »

dheera wrote: post #47
bufferoverflow wrote: post #2

You need to divide crime counts by population density. Otherwise you're just plotting population density.

Yes and no. Not dividing by population density ~ Probability I will become a crime victim by travelling through that area Dividing by population densitiy ~ Probability that I would be a crime victim if I live in that area

Not necessarily, people may (or may not? maybe it’s regional) be more likely to victimize strangers.

Re: Show HN: Play with an interactive heatmap of SF crime (and other cities)

#53

Post by rogers12 »

chatmasta wrote: post #49
SafemapTecnolgs wrote: post #4

Earlier quoted context omitted.

Thanks for checking out the site and for the feedback. It's definitely something we're looking into. It's kind of an interesting question though because it somewhat varies by crime category. Take car break ins, for instance - this is more of a constant factor than a population density scalar because the number of parking spots is generally fixed on a per-block basis rather than scaling with population density. I thin…

The number of parking spots may be static, but the number of potential thieves scales with population density.

Does it really? Some classes of crime have been narrowed down to the same 50 individuals. You can't model car break-ins as everybody in the area rolling the dice on getting a taste for breaking glass and grabbing things.

Re: Show HN: Play with an interactive heatmap of SF crime (and other cities)

#54

Post by aeturnum »

spacebanana7 wrote: post #36
aeturnum wrote: post #19

Earlier quoted context omitted.

It's the opposite - right? There are more gross crimes in the high-density area, but your chance of suffering one is much lower (all else being equal). Trying to apply statistics directly like this is generally inaccurate, but to the degree the numbers say anything it's the opposite of what you say.

Fair point, it's more complicated than I originally thought. Density increases the number of potential criminals you pass but also increases the number of alternative victims they could target. If you're a uniquely attractive/visibly wealthy personal walking home from a night out then the risk of passing more criminals dominates the advantage of alterative targets. After all, there's nothing really competing with you…

There's also a lot of evidence that a given individuals' chance of being the victim of a particular crime derives from their social situation. Most people who regularly do crime are used to doing crime in a way they can repeat, and those crimes most often target locals and people from the same social sphere. There are also plenty of factors that lead to the targeting of tourists or wealthy people, but most crime victims are poor and live in similar conditions to the person committing a crime against them.

Obviously this isn't every crime! People do have unlikely crimes happen to them all the time! Just that they're statistical anomalies and the population level statistics will mislead you about how high your risk is.

Re: Show HN: Play with an interactive heatmap of SF crime (and other cities)

#55

Post by Sohcahtoa82 »

davedx wrote: post #25
rachofsunshine wrote: post #6

Earlier quoted context omitted.

That's probably not the correct analysis, because the number you're trying to estimate is not P(a crime occurs near you), it's P(you will personally be the victim of a crime). Crime rate over density won't necessarily do that either (since the population density of a primarily commercial+touristy area, e.g. Fisherman's Wharf, is << the number of people who are present there on a given day), but neither does raw count…

As a tourist in SF recently I was interested in seeing the whole city, warts and all, and I did. I don't really understand why as a tourist you'd want to use this map for a short trip, unless you were going somewhere that's a literal war zone. Most cities just aren't statistically dangerous for a tourist unless you go out looking for trouble. You're much better off applying common sense than digging through digital m…

I dunno, I'd think car break-ins would at least be a very important statistic.

My wife and I will be spending a day in the Fisherman's Wharf area, and the statistics on car break-ins has me concerned, though a co-worker who lives in the Bay told me that if I'm parked in a parking garage, it's less likely I'll be a victim, as it's harder to smash-and-grab-and-go when you have to deal with a parking gate.

Re: Show HN: Play with an interactive heatmap of SF crime (and other cities)

#56

Post by mckn1ght »

autoexecbat wrote: post #42

Thanks for making this, it would be helpful if the city boundaries weren't so closely observed, most people don't care where the exact city lines are but have more of a feeling for the general metropolitan area as a blob

Pretty wild that you can intuit the city boundary by using the car break-in stat, it’s the most evenly and widely distributed one I saw.

Re: Show HN: Play with an interactive heatmap of SF crime (and other cities)

#57

Post by w10-1 »

Great work!

- The maps are pretty and scale nicely. The clarity and granularity of text is appreciated.

- The controls are excellent. I might put the copy and help in the same single title/menu panel (without "viewing:" as obvious)

Some other features I found myself wanting:

- Visually bound the map so you can see when it can't be moved in a direction. Think about what to do when the control panel is open and the user is trying to drag the map to see what's under the panel (instead of closing the panel).

- ability to sort data drill-down by number, to look at most prevalent

- using gradients for data starts to break down at low numbers. I wonder if you can start putting dots under some threshold

- time-range delta heat-maps: 2023 car break-ins vs 2022 (where green is improvement, red is worsening, and intensity is size of delta)

- surfacing qualitative aspects of data sources: one or many (only police?); and perhaps user feedback on quality of data

- curate super-categories, e.g., capturing all cocaine-related offenses, or distinguishing the stacked charges (loitering in the area of ...) from the operative ones (dealing), or crimes against (visiting?) strangers vs locals or friends. The data sources have their own arcane categorizing logic, and it's rarely what users actually want.

- color-code user-specified combinations: prostitution + drugs vs either alone

- Most of these relate to the kinds of questions users can answer with the maps, so if you have a (user-contributed?) panel with questions and their associated configuration sets, it would be very powerful and sticky.

- Then it would be nice to apply the same configuration-set to different cities, and perhaps to see some comparison across cities

Some things I wouldn't do:

- All-caps, tm? ok, but...

- I think putting safety under quality of life makes the product a bit less polarizing and hence more popular - which means adding other quality-of-life measures (e.g., zoning (residential/retail/manufacturing), cost/sf for housing, walkability scoring) E.g., it would be interesting to know which retail districts are super-safe.

Re: Show HN: Play with an interactive heatmap of SF crime (and other cities)

#58

Post by duskwuff »

microtherion wrote: post #17

It's interesting to see how certain crimes (e.g. Assault and Robbery) have hotspots that map perfectly onto BART stops (16th & Mission, 24th & Mission).

Possibly because the crimes are occurring aboard the train, so the exact location of the crime is unclear?

Re: Show HN: Play with an interactive heatmap of SF crime (and other cities)

#59

Post by autoexecbat »

whimsicalism wrote: post #20
microtherion wrote: post #17

It's interesting to see how certain crimes (e.g. Assault and Robbery) have hotspots that map perfectly onto BART stops (16th & Mission, 24th & Mission).

it’s not surprising if you’ve ever lived in that area

It is somewhat surprising actually. Presumably if there's an actual hotspot that police would be ever-present in the area until it dilutes out

Re: Show HN: Play with an interactive heatmap of SF crime (and other cities)

#60

Post by mindwork »

delichon wrote: post #28

Location based danger zone notifications would be helpful. "Warning: You are entering an area with a large number of reported muggings."

There is an app called Citizen that notifies you about crime happening near you in real time
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