Why is there so much confusion? There was slightly better news for May from a Panelbase poll which put her party 8 points ahead of Labour, but that still meant the Conservatives' advantage had nearly halved in a week.
Conservative's lead over Labour has halved to 9% from 18%, according to a Survation poll for the ITV news channel.
"The question is what is the alternative?"
Labour would get 257 seats, up from 229, the Liberal Democrats 10, up from the nine Tim Farron's party held when the election was called, the SNP 50, the Greens one and Plaid Cymru three.
YouGov's model draws on the data collected from around 50,000 panellists quizzed on their voting intention over the course of a week and uses a recently-developed technique called multilevel regression and post-stratification (MRP).
How trusted are the polling companies? If Wednesday's poll had used the previous poll's methodology, it would have shown the Conservatives' opinion poll lead narrowing by 6 percentage points, Panelbase said.
The pollster's MRP model is based on the fact that people with similar characteristics tend to vote similarly, but not identically, regardless of where they live.
But just 43 percent of those in this age group voted at all last time, far below the percentage of older voters.
"They are telling us they are going to vote this time but they have not done so before".
Nevertheless, statistically young people remain among the most apathetic, with consistently low electoral turnouts.
In the event of a Labour party victory, the direction of sterling is less clear, than it would be under a Conservative victory, where, the Jupiter managers add, that an uplift in its value is expected.
"We doubt that the Times/YouGov research is giving us the true picture about how many seats each party will win on June 8th", Kathleen Brooks, EMEA Research Director at City Index, wrote in a note. Smaller parties, including the Scottish National Party and Northern Irish parties, could win 83 seats, The Times newspaper quoted YouGov as predicting.
"Political context matters a lot in United Kingdom elections", Lauderdale said.
If the YouGov model turns out to be accurate, May would be well short of the 326 seats needed to form a government tasked with the complicated talks, due to start shortly after the election, on Britain's divorce from the European Union.