Selection bias in Vox pop interviews

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jimbob
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Selection bias in Vox pop interviews

Post by jimbob » Wed Nov 13, 2019 7:52 am

This struck me when the BBC visited my constituency, and the town of Buxton.

They were there in the middle of a weekday, which meant people with jobs would have been under-represented.

If you're asking questions about the attitude to Brexit, you're likely to get, and present a skewed impression of the local sentiment.

Whether this is unconscious selection bias or, simply a way of making a more provocative story, I'm not sure, but it probably does affect the debate.
Have you considered stupidity as an explanation

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Re: Selection bias in Vox pop interviews

Post by Woodchopper » Wed Nov 13, 2019 8:35 am

Yes. The people walking down the high street on a weekday afternoon and agree to be interviewed definitely won't be a representative sample.

If a TV producer were to take the time they could construct a narrative based upon the actual demographic profile of the constituency. But it'll be easier just to interview people they accost until they get something that'll pull in the viewers.

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Re: Selection bias in Vox pop interviews

Post by individualmember » Wed Nov 13, 2019 8:44 am

Woodchopper wrote:
Wed Nov 13, 2019 8:35 am
If a TV producer were to take the time they could construct a narrative based upon the actual demographic profile of the constituency. But it'll be easier just to interview people they accost until they get something that'll pull in the viewers.
Yebbut that’s not how tv works. I mean it can if you’re making a documentary and spending a couple of months on it, but 99% of the time the crew shlepping about trying to get members of the public to talk to them are sent out at probably 9-ish in the morning (or after a production meeting at 11-ish) * and have to deliver their selection, edited into a package, to the producer (in his/her nice warm office) by teatime.

ETA * then waste an hour trying to work out why the camera isn’t receiving sound from the microphone and trying to find a spare battery that actually has some charge in it and a mIni LED lamp that works and deciding to give up on those and hope the sun shines and the battery lasts.

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Re: Selection bias in Vox pop interviews

Post by Woodchopper » Wed Nov 13, 2019 12:15 pm

individualmember wrote:
Wed Nov 13, 2019 8:44 am
Woodchopper wrote:
Wed Nov 13, 2019 8:35 am
If a TV producer were to take the time they could construct a narrative based upon the actual demographic profile of the constituency. But it'll be easier just to interview people they accost until they get something that'll pull in the viewers.
Yebbut that’s not how tv works. I mean it can if you’re making a documentary and spending a couple of months on it, but 99% of the time the crew shlepping about trying to get members of the public to talk to them are sent out at probably 9-ish in the morning (or after a production meeting at 11-ish) * and have to deliver their selection, edited into a package, to the producer (in his/her nice warm office) by teatime.

ETA * then waste an hour trying to work out why the camera isn’t receiving sound from the microphone and trying to find a spare battery that actually has some charge in it and a mIni LED lamp that works and deciding to give up on those and hope the sun shines and the battery lasts.
Certainly, so to go back to the op, the people who appear on vox pop segments are unlikely to represent the population in the area.

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Re: Selection bias in Vox pop interviews

Post by individualmember » Wed Nov 13, 2019 1:35 pm

Woodchopper wrote:
Wed Nov 13, 2019 12:15 pm
Certainly, so to go back to the op, the people who appear on vox pop segments are unlikely to represent the population in the area.
I agree entirely. You have what people are going to be outside at the time and which of those are willing to talk on camera before you even get to how the questions are framed

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Re: Selection bias in Vox pop interviews

Post by mikeh » Wed Nov 13, 2019 8:10 pm

Surely these days you don't even need to send a camera crew out, you just hoik some spiel from twitter.

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Re: Selection bias in Vox pop interviews

Post by Stephanie » Thu Nov 14, 2019 12:25 am

Do we have any stats on the groups who voted for Brexit (employed, retired, etc)?
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Re: Selection bias in Vox pop interviews

Post by username » Thu Nov 14, 2019 1:49 am

There might be some in this.
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Re: Selection bias in Vox pop interviews

Post by Stephanie » Thu Nov 14, 2019 12:36 pm

username wrote:
Thu Nov 14, 2019 1:49 am
There might be some in this.
Thank you so much!
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Re: Selection bias in Vox pop interviews

Post by Vertigowooyay » Thu Nov 14, 2019 2:25 pm

Calm yourself Doctor NotTheNineO’ClockNews. We’re men of science. We fear no worldly terrors.

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Re: Selection bias in Vox pop interviews

Post by lsnduck » Thu Nov 14, 2019 3:23 pm

Vertigowooyay wrote:
Thu Nov 14, 2019 2:25 pm
But this is rather good...

https://twitter.com/i/status/1194376085812760576
I did that to someone once, sadly it was pre-recorded for radio rather than live for TV, so I'm sure it got binned.

I got grabbed outside a railway station during some period or other of rail carnage and proceeded to tell the woman how actually I think the service was quite good and how they do a decent job given the circumstances. It was not what she was fishing for.

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Re: Selection bias in Vox pop interviews

Post by individualmember » Thu Nov 14, 2019 3:33 pm

A few years ago I was walking along Oxford Street with my brother when we were approached for a vox pop, I declined and nipped behind the camera but my brother said sure... the question was about public sector finance for the arts, so my brother gave them a very earnest explanation of why funding is so important, then said 'and if that's not what you're after....' and gave them a very earnest argument as to why it's a terrible idea. I've no idea whether either was used.

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Re: Selection bias in Vox pop interviews

Post by Gfamily » Thu Nov 14, 2019 3:43 pm

individualmember wrote:
Thu Nov 14, 2019 3:33 pm
A few years ago I was walking along Oxford Street with my brother when we were approached for a vox pop, I declined and nipped behind the camera but my brother said sure... the question was about public sector finance for the arts, so my brother gave them a very earnest explanation of why funding is so important, then said 'and if that's not what you're after....' and gave them a very earnest argument as to why it's a terrible idea. I've no idea whether either was used.
I think the current PM did something similar about 4 years ago
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Re: Selection bias in Vox pop interviews

Post by Woodchopper » Fri Nov 22, 2019 3:26 pm

Stephanie wrote:
Thu Nov 14, 2019 12:25 am
Do we have any stats on the groups who voted for Brexit (employed, retired, etc)?
This is rather interesting.
https://twitter.com/jburnmurdoch/status ... 2197799939

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