It is undoubtedly true that the Lib Dems have gained support following the first television debate on 15 April, but most national opinion polls are useless in determining how the national share of the vote is likely to break down among the three parties.
The 95 per cent confidence interval for these polls is six percentage points (that is, plus or minus 3 per cent of the reported percentage for each party). The 95 per cent confidence interval gives us the range within which we can be 95 per cent confident that the "true" percentage of the national vote for a party lies.
Statistically, we cannot say any number within this range is any more or less likely to be the "true" percentage. Thus, if a party is reported by a poll to have 30 per cent of the national vote, it is equally plausible to conclude that their "true" percentage is as low as 27 per cent or as high as 33 per cent.
Therefore, since the reported percentages for each party are now bunching, meaning the 95 per cent confidence intervals often overlap, we can no longer say who is ahead or behind in the national polls and, over time, who is "gaining" or "losing" support.
We cannot give any rank order to the three parties: statistically, it is equally plausible that they could all be either first, second, or third. In the ComRes poll, it is equally plausible that the Conservatives could have as high as a 16-point lead over Labour (38 per cent versus 22 per cent) or as low as a four-point lead (32 per cent versus 28 per cent).
In reality, general elections are won or lost in a few key marginals, about which we can glean little information from newspapers.
Department of Sociology, University of California, Los Angeles, USA
The second so-called debate last week was a cross between the Who Wants to Be A Prime Minister show and Dad's Army.
The three contestants put on their best performance for the viewer's vote, each displaying their own qualities from the classic 1960s series; David Cameron reminded me of Private Walker, a slick-talking spiv, trying to sell us a load of old junk. Gordon Brown was Frazer, the Scottish undertaker who effortlessly exudes doom and gloom.
And Nick Clegg, despite his recent bombardment of adoration, perfectly took on the role of the boyish Private Pike, prattling on about what life would be like in his Liberal La La Land, and showing little grasp of the real concerns of the British people.
Just one more episode of the self-promoting spectacle to endure before the grand finale on 6 May, which will be a 24-hour TV extravaganza featuring an array of political pundits, analysts and forecasters, not forgetting the customary Swing-o-meter.
The winner of the contest wins a rent-free, five-year stay in No 10 Downing Street, whose threshold will greet its first elected tenant since the Blair family back in 1997. Sound the sirens now, I feel we're going to be raided.
Many thanks for your leading article "There is a strong case for not renewing Trident" (24 April). Yet there are still those in power who say we must keep "our independent deterrent". But it is not "ours", it is not "independent" and it is not a "deterrent". It is not "ours" since most British people have made it clear in polls that they do not want it. It is not "independent" since it uses missiles designed and made in the US, and could be launched only by using a US satellite system.
And it is not a "deterrent" since it will not deter the real threats of global warming, the population explosion, peak oil and greedy bankers.
Gordon Brown has become the Humpty Dumpty of British politics with his "When I use a word, it means just what I choose it to mean, neither more nor less" approach to reality.
He consistently presents aspirations as achievements, irrespective of the evidence, and remains dogged in his failure to recognise that substance requires a degree of self-awareness and analysis of all data, even that which critiques rather than that which merely bolsters an argument one is desperate to believe.
His tragedy is to have become the true heir to Blair in his disingenuity and regular economy with the truth, while lacking the permatan sincerity to fool all of the people all of the time.
Bradford, West Yorkshire
David Cameron has repeatedly claimed the UK's national debt is now "larger than Greece's". The implication is of course that we are in as deep a financial mess as is Greece. He fails to point out that the UK's GDP is about seven times as large as that of Greece. So, proportionately, our national debt is one seventh as large as that of Greece. His point is entirely bogus and it is time someone made him face up to this.
David Cameron says family is the most important thing in his life and also "the best welfare state".
As he and his wife are reputedly worth in excess of £30m, can I ask for the equivalent wealth package from the state? No, I thought not. It ill behoves a rich politician to refer to his even wealthier wife in the same breath as mentioning the welfare state.
Newhaven, East Sussex
As a former Tory voter, there is no way I would consider voting for them on this occasion. It is not just that David Cameron has copied the social policies of his Lab-Lib opponents in favour of political correctness, but in an area where he could have legitimately followed a broader political consensus he has been found wanting.
The Conservative policy, with a few courageous prospective MPs as exceptions to bring back hunting, is neither morally acceptable nor electorally sensible. Though predators on occasions may need to be controlled to protect farm livestock or endangered species, this should never be seen as an excuse for some form of perverted entertainment, but should be carried out humanely by properly qualified marksmen. Most of the electorate want to see the Hunting Act properly enforced rather than repealed.
Potters Bar, Hertfordshire
The impact of voting Green will be to risk letting in pro-hunting Tory candidates in marginal seats and a Tory government which will sweep away all the progress made on animal welfare.
Caroline Lucas and her followers pose danger, as did Ralph Nader in the 2004 US election when he took large numbers of progressive votes in swing states, allowing George Bush to sweep to victory. The message is clear: vote Green, get blue.
Atheists and the afterlife believers
As someone who tries hard to be a Christian and therefore believes in God and an afterlife, I find the rantings of Johann Hari (Comment, 21 April) and other diehard atheists highly amusing.
After all, there is no absolute proof, scientific or otherwise, that God exists, so the converse is also true; there is no proof that he does not.
Most of those with a religious faith will admit to having doubts, from time to time. Their faith "wobbles" for various reasons. But atheists, whose views also have no scientific evidence to support them, are always so certain they are right.
Any human imagining of what an afterlife may be like, from whatever period and culture it comes, is meaningless. But the atheist view that death brings oblivion poses far more questions than it answers.
Johann Hari's article about the non-existence of heaven was spot-on. It is sad that most people need the concept of an afterlife; that belittles our precious lives on Earth.
But I do not share Johann's opinion about "the empty awfulness of death". We were "dead" for billions of years before we were born to experience that brief, beautiful flash of consciousness we call our life. During my pre-life, I do not recall any empty awfulness and I'm sure I won't post-life either.
Brains needed, not brawn
Your leading article "Science and the establishment" (14 April) mentions the Royal Institution's debts but doesn't discuss how vital it is to the nation that the RI find the resources and management needed to do its job more effectively.
Britain has few mineral resources, high labour costs and not much land. Whether listing to left or right after May's election, the good ship Britannia is either going to drift grubbily downstream as a floating call centre or we need to find something to be better at than other countries.
We have no alternative but to choose brains over brawn. The Royal Institution is in a position to stimulate a British renaissance by encouraging a generation into science. At this critical juncture, a few good people with deep pockets could make a national difference that would reverberate for decades.
Airline that flew to the rescue
The media is full of stories about how badly the airlines have treated travellers stranded by the closure of British airspace due to the volcanic ash cloud. We can provide balance, because we were treated excellently by Emirates airlines.
Our flight on 15 April was cancelled as we were in the check-in at Dubai airport awaiting our return flight after a six-day holiday. Within two hours, we had been put into an airport hotel and provided with meal tickets. There were no flights possible 24 hours later so they extended our stay for another 24 hours. This daily extension continued every 24 hours until Tuesday evening last week when it looked as if the airspace was being re-opened.
We were told to pack up and be ready to leave at any time. There was a knock on the door at 2.30 on Wednesday morning and we were told to get on a bus to the airport. We were put on a 7.45am flight – a new Airbus 380 – filled with other stranded passengers. We landed at Heathrow on Wednesday at lunchtime. There, we found our airport parking had been extended for seven days at no extra cost.
This behaviour restores one's faith in human nature. I have only praise for Emirates airlines who treated us with respect even when they were under severe pressure.
I suspect I am not alone in finding a substantial silver lining in the ash cloud. I have just run an international conference on Applied Theatre. Our two speakers, from India and the USA, had their flights cancelled. So did several other key invitees.
So they participated via interactive Skype. Students kept blogging with details of all the sessions so those who could not make it were able to follow the conference from car-parks in Calais and pick-up points in Madrid.
With new technology, the conference experience was hardly impaired. We have learnt we can cut our carbon footprint and our costs by running far more conferences in this way.
Central School of Speech & Drama, London NW3
Having paid £1,000 to get my daughter and her fiancé back from Australia I am not happy to think that the government might accede to Richard Branson's irritating demands for compensation. The government means the taxpayer and that means me. To Branson, £50m is a drop in the ocean; £1,000 is not a drop in the ocean to me.
Tuned in to music
According to Rhodri Marsden (14 April), media companies must make their more obscure content "easier to obtain than illegally hosted versions". It took me less than a minute on iTunes to find "Sacred Songs", Daryl Hall's supposedly obscure 1980 collaboration with Robert Fripp, in which Rhodri was "mildly interested".
That's pretty easy and, to quote one of the album's song titles, "Without Tears". It's good news that your writer was prepared to pay for such an obscurity, but as for speed and ease of access, where's the problem?
Universal Music, London W14
Count on chaos
I am completing my application to sell back green energy from my PV solar panels to the national grid. I have to provide a unique identifier for my meter. This "MPAN" turns out to be a 21-digit number. The population of the Earth may rise to ten billion by 2080 (WHO medium estimate).
So there are, on average, more than a billion available export meter numbers per individual. With this risk of me making a mistake, I suspect that a lot of forms will have to be returned to be corrected.
Dr Andrew Stainer-Smith
No war debt
There was no Second World War debt to the USA (letter, 24 April). Lease-Lend was free. But it did take 60 years to pay off a post-war loan given after Harry Truman signed the cancellation of Lease-Lend the day after VJ Day. He later said he had not realised the significance of that signature.
Derek J Cole
St Leonards-on-Sea, East Sussex
You don't say
It is curious that some of your readers (letters, 20 and 23 April) think that anyone might have any control over how the English language may develop. Surely another example of hope triumphing over experience.
Arkengarthdale, North Yorkshire
Perspectives on climate change
On the day designated as Climate Change Day in the election campaign, we urge all political parties to commit to an international climate agreement that will also provide for the world's poorest people.
Climate change is already causing severe suffering in developing countries which have done least to cause it. If left unmanaged it will derail and reverse development.
The Copenhagen Accord states that global warming must be limited to no more than two degrees. So it is vital that the international community now achieves a comprehensive UN climate agreement covering all countries to implement this goal. Such an agreement must commit developed countries especially, including the EU members, to deeper cuts in emissions than those now on the table.
Critically, additional financing is needed to increase access to knowledge and skills by the poorest countries so they can adapt to the already unavoidable consequences of climate change.
A global coalition for action on climate change cannot be secured at the expense of development. Rich countries must demonstrate that low-carbon growth is possible.
Any agreement must provide for greatly increased financial assistance, and for the sharing of technologies, to help the poorest countries adapt to climate change, reduce deforestation and make lower carbon investments.
It is imperative that this assistance includes new and additional finance, not just a reallocation of existing commitments to promote development.
We are increasingly concerned that some countries are refusing to commit to additional finance for climate change and instead seem intent on taking climate assistance solely from monies already allocated for development. Such evident injustice would be unacceptable and would jeopardise any future climate agreement.
The two defining challenges of our century are overcoming poverty and managing climate change. If we fail on one, we will fail on the other. Over recent years British leadership has done much to advance global progress in both areas. It is vital for the world that this is maintained, whoever forms the new UK Government.
Kofi Annan, Chair, Africa Progress Panel, and former UN Secretary-General
Wangari Maathai, Chair and Founder, Green Belt Movement, and 2004 Nobel Peace Prize Winner
Nicholas Stern, IG Patel Professor of Economics and Government, London School of Economics and Political Science