Despite methodology biased against shy, young and less-well-off, Ipsos MORI / STV poll shows ‘Yes’ vote holding up again

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From the Scottish Public Opinion Monitor for STV News on 31 May 2017:

‘Among those who would be likely or certain to vote in an independence referendum, 47% said they would vote Yes (-3 pts from March) while 53% would vote No (+ 3 pts from March).’

https://www.ipsos.com/ipsos-mori/en-uk/snp-look-set-be-biggest-party-upcoming-election

However, they interviewed via landline telephone and not online. I’ve already written about the effects of the two methods of data collection but the key point is that the former tends to generate conservative, status quo, ‘shy’ responses especially on controversial topics such as this so the results may be understating support for independence. Also, the young and less well-off are less likely to have landlines and more likely to be Yes supporters. See this for a fuller explanation using the EU referendum outcome as an example:

 ‘There’s a big difference between the online and telephone polls on the EU referendum – with online polls showing the sides neck-and neck and telephone polls showing about a 15% gap in favour of ‘remain’. Why? It’s striking that both methodologies right across the different polling companies give about the same number to the ‘leave’ campaign, around 40%. The difference is in the ‘remain’ number, which is around 52% from the telephone polls but only 40% for online polls.’

So, commonly, telephone surveys generate conservative, negative or status quo returns. Respondents are more likely to say no to a question about a big change of some kind.

In another YouGov report also referred to in:

Why the 49% supporting independence in today’s BMG poll may be more accurate and much more optimistic than other recent polls suggesting a wider gap.

we read:

‘Now however we can reveal a real, significant and evidence-based difference between the two methodologies that explains why they are divergent and why it is online that appears to be calling it correctly.’

So, 47% may be conservative but, anyway, is still too close to call and the independence polls continue to be so despite an apparent fall in SNP support. Not all Yes supporters need to be SNP supporters.

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2 thoughts on “Despite methodology biased against shy, young and less-well-off, Ipsos MORI / STV poll shows ‘Yes’ vote holding up again

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