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Poll: How old are you?

news.ycombinator.com

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Re: Poll: How old are you?

#101

Post by timr »

tokenadult wrote: post #93
timr wrote: post #71

Interesting comparison from 1998: http://slashdot.org/poll/421/My-Age-is In 1998, 22% of respondents were ages 16-20, 53% were in their 20s, 15% in their 30s and 5% over 40. As of this writing (and assuming that I did my arithmetic correctly), ~7% of respondents on this poll are ages 16-20, ~60% are in their 20s, ~25% in their 30s, and ~7% are over 40. Obviously there are a lot of caveats here, but the slight increas…

As I commented previously when we had a poll on the ages of HNers, the data can't be relied on to make such an inference. That's because the date are not from a random sample of the relevant population. One professor of statistics, who is a co-author of a highly regarded AP statistics textbook, has tried to popularize the phrase that "voluntary response data are worthless" to go along with the phrase "correlation doe…

Well, as I said before -- there are lots of caveats. But I hope that professor loses his bid to introduce another sound-bite into the statistics world, because it's not correct to blindly say that the data are "worthless" simply because they're voluntary responses. We make useful inferences from voluntary response data all the time (c.f. every political poll ever conducted, where people can choose not to respond). The correct question is: does the voluntary response process result in a systematic bias that will affect the conclusion in question? But that's neither short, nor catchy.

In this case, there's a strong argument to be made that the samples could skew young (if for no other reason than because younger people frequent sites like HN more than older people). It's also quite possible that the demographics for HN and for slashdot are different in a way that would make the HN audience skew younger. But the voluntary response process itself? I think it's a stretch to claim that it'll cause a measurable bias in age distributions, across two different surveys, spaced a decade apart. You'd have to argue that younger people in 2011 are more likely to answer a poll than younger people in 1998 were to answer a poll. Possible? Sure. The most likely source of error here? Nah.

In other words, if you're going to pick (and you should!), pick on the BIG, OBVIOUS differences between the data sets...not the little ones.

Re: Poll: How old are you?

#102

Post by jkent »

tokenadult wrote: post #93
timr wrote: post #71

Interesting comparison from 1998: http://slashdot.org/poll/421/My-Age-is In 1998, 22% of respondents were ages 16-20, 53% were in their 20s, 15% in their 30s and 5% over 40. As of this writing (and assuming that I did my arithmetic correctly), ~7% of respondents on this poll are ages 16-20, ~60% are in their 20s, ~25% in their 30s, and ~7% are over 40. Obviously there are a lot of caveats here, but the slight increas…

As I commented previously when we had a poll on the ages of HNers, the data can't be relied on to make such an inference. That's because the date are not from a random sample of the relevant population. One professor of statistics, who is a co-author of a highly regarded AP statistics textbook, has tried to popularize the phrase that "voluntary response data are worthless" to go along with the phrase "correlation doe…

Do you have reason to doubt the validity of this particular survey?

I personally can't see significant problems of this over any survey technique.

There are problems with questionnaires and self-responses, sure, but to say they are worthless is to exclude an entire category of data based on a selective opinion. Horses for courses, if you like.

Many statistical methods are available, some of which are more appropriate than others in particular situations. There is little wrong with convenience sampling if what is of primary importance is convenience, e.g.

(That being said, I'd be careful with taking the results of this poll and applying it to any technology site and therefore the interwebs etc. Inferring from this data that we don't have an ageing population problem would be dangerous).

Re: Poll: How old are you?

#103

Post by obfuscate »

Alex3917 wrote: post #96
tokenadult wrote: post #93

Earlier quoted context omitted.

As I commented previously when we had a poll on the ages of HNers, the data can't be relied on to make such an inference. That's because the date are not from a random sample of the relevant population. One professor of statistics, who is a co-author of a highly regarded AP statistics textbook, has tried to popularize the phrase that "voluntary response data are worthless" to go along with the phrase "correlation doe…

"voluntary response data are worthless" There are ways of correcting for non-responders though. For example, there is the Monitoring The Future study that asks high school kids about their history of drug use. Almost everyone who is in school that day answers the questions, but that still leaves everyone who was absent that day. So what they do is they ask the kids the number of days of school they have missed so far…

Well, they can assign reported history of drug use correctly. Do they do anything similar to correct for lying, or just label their data as "self-reports of drug use"?

Re: Poll: How old are you?

#104

Post by sabat »

artiegold wrote: post #24

51-55 Better than dead. Much.

It's funny how when you get here (I'm 47) you realize what a bunch of BS all the age complaints are. You appreciate life so much more, and -- speaking for myself -- are as full of energy and ideas as ever.

Re: Poll: How old are you?

#106

Post by AndyKelley »

jefe78 wrote: post #70

Why were you wondering about this in the SHOWER?!

The shower is a great place to think about all sorts of things. The constant din of the water falling down, the warm water, and the fact that you are forced to stop for a few minutes give your subconscious mind a bit of time to organize itself and reveal what it's been pondering.

Re: Poll: How old are you?

#107

Post by petercooper »

timr wrote: post #71

Interesting comparison from 1998: http://slashdot.org/poll/421/My-Age-is In 1998, 22% of respondents were ages 16-20, 53% were in their 20s, 15% in their 30s and 5% over 40. As of this writing (and assuming that I did my arithmetic correctly), ~7% of respondents on this poll are ages 16-20, ~60% are in their 20s, ~25% in their 30s, and ~7% are over 40. Obviously there are a lot of caveats here, but the slight increas…

[..] is nothing like you'd expect if everyone who started in their 20s in 1998 stuck around until today.

I have an interesting observation around this. I got started in this industry "for real" in the late 90s and worked for some "new media" companies (as they were known at the time!). I also read a lot of the magazines that featured things like "The 50 Most Important People Online" and similar crud.

And.. recently I tried tracking down people whose names I could remember back then. Few were still involved with tech or Internet-specific work. And of those "important" people, few were names I recognized.

To me, at least, it seems like the group of people working online has changed a great deal in the last 13 years. And I'm surprised by that.

Re: Poll: How old are you?

#108

Post by feral »

Alex3917 wrote: post #96
tokenadult wrote: post #93

Earlier quoted context omitted.

As I commented previously when we had a poll on the ages of HNers, the data can't be relied on to make such an inference. That's because the date are not from a random sample of the relevant population. One professor of statistics, who is a co-author of a highly regarded AP statistics textbook, has tried to popularize the phrase that "voluntary response data are worthless" to go along with the phrase "correlation doe…

"voluntary response data are worthless" There are ways of correcting for non-responders though. For example, there is the Monitoring The Future study that asks high school kids about their history of drug use. Almost everyone who is in school that day answers the questions, but that still leaves everyone who was absent that day. So what they do is they ask the kids the number of days of school they have missed so far…

Their ability to correct for the missing kids, is presumably because they can assume that the kids missing are missing at random (proportional to their attendance rate.)

This is very different, because while there is some data missing, it is missing at random (albeit weighted), and can thus be corrected for.

If it was the case that kids avoided coming into school that day, because they knew the survey would be held, it would be a very different problem.

Re: Poll: How old are you?

#109

Post by Alex3917 »

obfuscate wrote: post #103
Alex3917 wrote: post #96

Earlier quoted context omitted.

"voluntary response data are worthless" There are ways of correcting for non-responders though. For example, there is the Monitoring The Future study that asks high school kids about their history of drug use. Almost everyone who is in school that day answers the questions, but that still leaves everyone who was absent that day. So what they do is they ask the kids the number of days of school they have missed so far…

Well, they can assign reported history of drug use correctly. Do they do anything similar to correct for lying, or just label their data as "self-reports of drug use"?

"Do they do anything similar to correct for lying"

There is an entire literature on the validity of self-reported drug use that they take into account. For example, there is a phenomenon called recanting, where someone will admit to using a drug one year and then deny it in future years. They correct for this by ignoring when someone recants if they have already admitted to using the drug on at least two previous surveys. (Which would be administered at least two years apart.)

What they found was that the people most likely to recant were the ones who got jobs where they would now be fired for admitting drug use. For example, cops recanted drug use after previously admitting to it at twice the rate of the general public. So that's how they made the decision to discount recanting for people who had already admitted to drug use twice or more times.

As for people who try to lie and claim they are taking drugs that they haven't been, this is corrected for by asking about the same drug multiple times in different ways. I think they may also salt the questions by asking about drugs that don't exist.

You can obviously read all about the methodology of Monitoring the Future by downloading it, and here is an enormous PDF with tons of studies on the validity of self-reported drug use in general:

http://archives.drugabuse.gov/pdf/monographs/monograph167/do...

All in all the methods they are using seem fairly accurate. It would definitely be a little higher if they corrected for more stuff, so for example when they say that 82% of Americans have used marijuana, it's actually probably closer to 85 or 86% when you correct for additional things that they haven't.

Re: Poll: How old are you?

#110

Post by ilamont »

kmfrk wrote: post #79

I'd rather like to see pg answer what age demographics comprise YC's start-ups. That data would be awesome (and probably daunting).

In one of the 2005 classes, everyone was 23 or younger:

http://www.paulgraham.com/sfp.html

Not specific to YC, he has this to say about older startup founders:

The other cutoff, 38, has a lot more play in it. One reason I put it there is that I don't think many people have the physical stamina much past that age. I used to work till 2:00 or 3:00 AM every night, seven days a week. I don't know if I could do that now.

Also, startups are a big risk financially. If you try something that blows up and leaves you broke at 26, big deal; a lot of 26 year olds are broke. By 38 you can't take so many risks-- especially if you have kids.

From: http://www.paulgraham.com/start.html

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