This week’s YouGov poll for the Sunday Times is now up on their website here. Topline figures are CON 33%, LAB 38%, LDEM 11%, UKIP 11%. The five point Labour lead is their lowest this year (the last time YouGov’s Labour lead was this small was back in November 2012). Obviously it could be a bit of a blip – polls have a margin of error – but it fits in with the recent trend of Labour’s lead narrowing a bit as UKIP come off the boil.

The rest of the poll had some interesting questions on immigration. 56% of people think that immigration into Britain has been bad for the economy, with only 19% thinking it has been a positive factor. However, on balance immigrants are seen as harder working than people who are born in Britain. 32% of people think that immigrants who come to work here are harder working, 12% less hard working, 46% much the same.

Asked about various groups of immigrants, 70% of people think we should allow fewer (or no) low skilled workers to come to Britain, 59% think that we should allow fewer relatives of people already living in Britain to come here to join relatives. People are actually far more positively disposed towards other immigrant groups – only 28% want to see a reduction in high skilled immigrants looking for well paid jobs, only 27% want to see a reduction in foreign students coming to study in British universities. Asylum seekers split opinion – 42% want to see a reduction in the number of people fleeing persecution allowed to come here, 47% are content with present numbers or would allow more.

Viewed as a whole it suggests people are far more positive about some types of immigration that you would think. It’s one of those times that, in hindsight, you wished you’d asked an extra question – in this case to find out what proportion of total immigration people think is made up of those groups. Given overall public hostility towards immigration I imagine they think it is mostly unskilled and relatives, rather the skilled workers and students they are apparently well disposed to, but it would be good to test.

Asked about specific government policies on immigration, views are once more the typical anti-immigration responses: 71% support requiring a £3000 bond for visitors from high risk countries, 84% support the idea of forcing benefit claimants to learn English or risk losing benefits.

In the Sunday papers there was also a new Opinium poll for the Observer, which had topline figures of CON 27%(nc), LAB 37%(+1), LDEM 7%(nc), UKIP 19%(-1). No sign of a narrowing in the polls there, although worth noting that the higher level of UKIP support is normal (Opinium are typically one of the companies that show the highest levels of UKIP support, something that they have said is probably due to them not using any political weighting).

Finally there was an ICM poll in the Sunday Telegraph, largely covering recent benefit changes and the spending review. 87% of people supported stopping benefits if people won’t learn English, 53% supported making people wait 7 days for benefits. 64% support a cap on the cost of benefits that excludes the state pension, 23% think it should include the state pension. However, 56% would also support means testing age related benefits like the winter fuel payment and free television licence. ICM don’t ask voting intention for the Sunday Telegraph, instead asking respondents to predict what they think the shares of the vote will be at the next election – answers this month were Conservatives 29%, Labour 34%, Lib Dems on 15% and UKIP on 13%.

Last year I wrote an article on How Not To Report Opinion Polls. It included advice on ignoring small cross breaks, margins of error and not cherry-picking. That is, if there is a long data series with lots of noise and random error, don’t pick out the one random outlier than supports your case and ignore the rest.

There is a classic example in the Guardian today. John Harris writes about polling of young people and says they are voting Tory. He writes: “One recent YouGov poll put support for the Tories among the 18-24s at 31%, with Labour trailing at 27%. By way of a contrast, Tory support among those aged 40-59 was at 29%, with Labour on 40%. In other words, the time-worn wisdom about politics and the young may be in the process of being turned on its head.”

Well, yes, one recent YouGov poll showed that. This one. However, other YouGov poll this month have tended to show Labour leads amongst young people and the Conservatives doing better amongst older people, a far more normal pattern. The poll the Guardian linked to was not typical of recent polling. On average YouGov’s daily sample contains around about 150 people under 25, about a third of which say don’t know or that they wouldn’t vote. This means the daily voting break for under 25s is based on about a hundred people, and has a margin of error of plus or minus 10 points. In other words, if a party actually had a lead of around about 8 points amongst young people, then random error alone will spit out polls showing leads of between plus 28 and minus 12. You can’t just take one out of context that happens to show figures you like.

Taking an average across the whole of June so far YouGov’s crossbreak for under 25s has the Conservatives on 31%, Labour on 38% – a significantly higher level of Labour support. Even that needs some caveating though. Opinion polls are weighted to be representative of the country as a whole, they are not necessary weighted so that the crossbreaks are internally representative. For example, overall there will be the correct number of people with a C2 social class, but there may be too few old people who are C2 and too few young people, or whatever. In theory this should even out over time, but there are no guarantees.

If you really want to know about the views of a particular sub-sample of the British population you need polling specificially aimed at them. Luckily enough, the Sun commissioned a specific YouGov poll of young people earlier this month, which was specificially weighted on things like education and employment status and level of educational qualification. It didn’t ask voting intention, but it did ask young people which party they thought best reflected their views – the results were 23% Labour, 12% Conservative, 7% Lib Dem, 7% Green, 6% UKIP, 39% none or don’t know.

In short, all the other findings that John Harris writes about on social and economic issues are fine (and are largely drawn from MORI’s generational data based on very large aggregate samples), but the idea that the Conservatives are suddenly the leading party amongst young people is really not true.

The monthly ComRes telephone poll for the Independent is out tonight, and has topline figures of CON 30%(nc), LAB 36%(+2), LDEM 10%(nc), UKIP 14%(-3). As with other recent polling ComRes show UKIP coming off the boil a bit after their post-local election high, but still well above the levels of support they had earlier this year. Full tabs are here.