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Comment by erex78 | Hacker News Reader

This is cool and a nice idea / UI, but it seems to bubble up populations centers. Needs to normalize for population somehow. (https://xkcd.com/1138/)

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Maybe there should be a widget that biases for less dense areas or does it proportionally, but the results aren't necessarily wrong as-is. A 2M+ population city with 20 <special interest group> meetups on a given weekend doesn't have more proportional interest in the topic than a 200K+ city with 2 <special interest group> meetups, but it still has 10x the total amount of activities for a resident to go to. I guess it depends on if the person is trying to figure out the absolute amount of activities available to them or the extent to which that activity dominates the culture of the area. I'd personally want to use the tool to figure out the absolute value.

One solution would be to stratify the results by population density

Yup that's definitely true, population centers rank highest for most topic lists (especially New York where meetup.com was founded)

The original use-case I envisioned for something like this is someone deciding which cities they might like to move to by choosing cities that have a lot of people with shared interests. So should the metric for that be total people that are part of a topic, or the % of total city population engaged in that topic? I've currently chosen the former, but interested in what others might think.

Thanks for the feedback,

-pH+

I agree with erex78. The former measurement doesn't tell me much; I already know what cities have the most people.

The latter measurement better indicates the probability of a chance encounter with someone who has your shared interests.

Yeah that's a good point. I like scribu's point that it can be somewhere in between. I'll have to think on that a little.

Usually (taken from erf/error based on sample size), something grows proportional to the square root of the sample size. If using raw sample sizes, you can apply a square root to that sample size before using it (meters its impact).

> So should the metric for that be total people that are part of a topic, or the % of total city population engaged in that topic?

Ideally, both. You want to have a community with at least N people, but cities with a high % should rank higher.

Could also account for the number of total meetup.com members in that place.

Hmm interesting, I'll give that some thought. Thanks!

You could have a toggle where you divide by the overall population of each city. So basically let the user switch between percentage and absolute.

Another ranking to consider is the h-index metric for academic papers (https://en.wikipedia.org/wiki/H-index), where you use the number of members of each meetup group in place of citations. So a city with a score h has h meetups each of which has at least h members.

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