Hacker News Reader

Comment by nohuck13 | Hacker News Reader

Last 4 digits of SSN is particularly flagrant. I could almost believe (if I wanted to give them the benefit of the doubt, which I don't, particularly) that they are using name and email as good-faith identifiers to let me opt out. After all, they need to identify me with _something_. But what could they possibly be doing with SSN unless they have offline credit score information obtained from some third party, which they couldn't previously link confidently to my advertising profile, and now they can?

View on HN

Is a 4 digit SSN number suffix really enough to be helpful to them in that regard? I guess they could find all "jcater"s with those 4 digits and make assumptions, but that is far from unique.

Yes.

ZipCode + SSN is enough to identify you, even without your name, close to 100% of the time. Toss in your name and I'd be amazed they'd ever got a false positive. I'm [honestly] not sure why they even bother asking for a mailing address other than to go from 99.9% confidence to 100%.

Fyi, there is ~8k people [on average] in a zip code. The odds of your name and SSN repeating inside a zip code is low. Name tho? Name could happen with reasonable odds. I used to know someone in my zip code with an identical first/last [not middle] name.

I'm going to give you the benefit of the doubt and assume you misread the post you are replying to, which referred to the last 4 digits of a SSN, and incorrectly assumed we were talking about full SSNs. Because otherwise your statement is absurdly wrong.

If there are 10,000 possible 4 digit combinations and 8,000 people in a ZIP code on average, the odds that someone else will share the last 4 digits of my SSN is 1-(1-1/10000)^7999 which comes out to 55%. So in reality, more often than not, you will share the last 4 digits of your SSN with someone in your zip code.

Also, there are a few zip codes with 100,000+ people in them, and many zip codes with 50,000+ people in them. These zip codes account for many millions of people. You are guaranteed that nearly every resident will share the last 4 digits of their social security number with at least one other person in these zip codes.

Yes, I was rushing and didn't read all that clearly.

It is one way you verify your identity with credit card bureau.

I entered it because I'm moving to an unspecified state soon. So if they want to think I'm in Indiana, let them.

You know, the second you login to this account from your new unspecified state, pg will know what state it is.

I'm reasonably certain he's not sharing his data with Acxiom, but I'm also reasonably certain you were planning on visiting other websites once you get there.

Reply on news.ycombinator.com