Politicians always say they are not influenced by opinion polls and will invariably employ the cliché learned in Evasive Answers 101: “Opinion polls are a snapshot in time.”

But from long experience, nobody pores or obsesses over the results as diligently as party strategists and number-crunchers. The proof of that particular pudding is the fact that political parties commission private polls regularly themselves. And polling has become such an ingrained part of politics in the US and elsewhere that nothing moves without that data to back it up.

The snapshot in time stock phrase is largely accurate, as polls only have meaning at that particular moment. There is also artifice to them, as people are often asked their voting intentions at a time when no election is on the horizon. Many people have not turned their thoughts to party support.

For many voters, the political thought processes really only crystallise close to polling day, with many making their minds in the final day. That’s why you will see that late opinion polls are often the most accurate.

For the first time, The Irish Times will be making available the full results of an Ipsos/mrbi poll in digital format, which will allow it to be accessed by digital consumers of our political news and opinion.

It will allow readers to access the raw data and discover the breakdown of party political support in Ireland in categories such as region, gender, social class and age.

You will see for example that Sinn Féin is surfing on a demographic wave at present and attracts very strong support from younger voters – mostly male but increasingly female. They tend to be drawn from blue-collar social categories - backing which is increasingly encroaching into support bases associated with Fianna Fáil and Labour.

In contrast, the age profile of Fianna Fáil’s support remains very high, which should send out warning signals to a party in terms of its future planning. The party does not have sufficient appeal with the type of voter it will need to connect with if it is to effect its recovery.

Irish Times Political Editor Stephen Collins’s analysis elsewhere gives an excellent overview of trends and movements revealed in the poll.

There should be a few words of warning added in. Younger voters tend to vote far more infrequently than those aged 35 and over, with the 18-to-24 cohort particularly remiss. The opposite is true for middle-class voters, as well as those from a farming or rural background.

Analysts usually take those factors into account. They have to, because they can deflate the actual support levels a party will have in an actual election.

There is also the hard-to-measure phenomenon of the “fashionable party”. During the boom years, more people stated they would support Fianna Fáil than actually supported them, and some polling organisations made adjustments made on that. When the economy collapsed, the poll “bounce” disappeared.

All of those factors conspire to alter results. For example, Sinn Féin has been the stellar performer in opinion polls over the past two years, with its support levels almost doubling to over 20 per cent.

That is good news for the party. However, there is always a significant gap between its opinion poll performances and its actual vote. For example, in the May local elections, the last opinion poll put support for Sinn Féin at 20 per cent, where the actual out-turn was just over 15 per cent (which was still a substantial gain for the party).

The Labour Party might also have experienced that "bounce" in the past. Not any more. After bottoming out last year at 6 per cent, the party's support has increased to 9 per cent. And given the popularity of its new leader Joan Burton at the moment, the party should expect to claw its way back into low double figures – its natural support level.

Fine Gael has taken a hit this time. Support of 24 per cent seems to be a low plateau for it these days – it has hit that low three times since February 2011.

But the figures are arguably more worrying for Fianna Fáil. After making some recovery it has effectively been on a flatline for the past year, and Micheál Martin’s figures suggest his aura is beginning to flag.

In that context, the party desperately needs a fillip – and that's why it has invested so much time and effort in getting Ivan Connaughton over the line in the Roscommon-South Leitrim byelection. If he fails tomorrow, it will lead to loud muttering within the Fianna Fáil ranks.

Equally, if Cathal King's performance in Dublin South West is a couple of notches short of emphatic, it might also take some of the sheen off Sinn Féin's magnificent year.