Opinion polls for the Scottish elections all point to one thing - a decisive victory for Nicola Sturgeon and a second SNP majority at Holyrood. But aside from the headline figures, here are six things we have learned from the pollsters.

Read: Five constituencies to keep an eye on in the Holyrood election

Tax is not a gamechanger.

Read: New powers over tax prove key battleground in historic Scottish election

The Lib Dems and Labour announced their plans to put 1p on the basic rate of income tax back in February but the policies appear to have had little impact on the polls despite the issue being billed as pivotal by some. Voters appear divided over taxation, with some polls showing support for a general income tax rise to improve public services and others suggesting the majority back keeping tax rates as they are.

But the independence referendum and its aftermath was.

Read: Independence views still key to half of Holyrood voters

According to Ipsos MORI's polling, a clear spike in support for the SNP can be seen in surveys conducted immediately after the September 2014 ballot, rising from just under 40% to between 50% and 60%. In contrast, Labour experienced a drop from support of about 30% to around 20% - a fall from which the party, try as it might, is yet to recover. Meanwhile, the referendum, which achieved a turnout of almost 85%, is almost certainly the reason why turnout at this year's Scottish election could climb to over 60% for the first time.

Tories can be popular in Scotland.

As the Tories have made gains, threatening to overtake Labour as Scotland's second party, Ruth Davidson has continued to enjoy some positive ratings across age groups and with both men and women - quite a feat for a Conservative leader in Scotland, according to some observers. A recent Survation poll showed she can even lay claim to being the most popular leader among the over-60s. But Ms Davidson has not quite reached the dizzy heights of Nicola Sturgeon, who, according to YouGov data analysis last year, polled as Scotland's "most beloved person".

The regional list is more important than ever.

Read: How regional list vote will play crucial role in Holyrood poll

With the SNP expected to grab most of the 73 constituencies, the other parties are homing in on the 56 list seats. Recent polls have shown Labour and the Tories are running neck-and-neck on regional voting intentions, meaning the vote could determine who comes second. A YouGov survey in February, for example, pegged both parties at 20% in the regional vote - how that translates into seats will depend on how those votes are spread across Scotland's eight regions.

The Greens are set for their best-ever Scottish election.

Read: Greens hope to convert 'extraordinary growth' in support into Holyrood seats

Thanks to strong polling on that list vote, the Greens are feeling confident and are hopeful of winning a seat in every region in Scotland for the first time. Recent surveys have put support on the regional vote as high as 10% - pushing the Lib Dems into fifth place in terms of voting intention share. The Greens' hopes of turning those list votes into seats will also depend on how well spread out their support is across the country.

But the same can't be said for the Lib Dems.

Polling indicates the Lib Dems are yet to recover from entering coalition government with the Tories at Westminster in 2010. Analysis shows its Holyrood election support fell away from more than 20% after the 2010 general election to around 10% by the end of that year, and has never risen above that figure since. That fall in support saw the number of Lib Dem MSPs drop from 16 to just five in 2011, with some pollsters predicting the party could return even fewer this time round.