The candidates and their volunteers are wearing out shoe leather and rasping knuckles on doors.

They say it's effective.

Labor's Alicia Payne who is standing in the electorate of Canberra said research had shown it was a better use of time than leafleting in a public square or phone bashing.

"It's the most valuable use of our time," said Jon Lawrence, who is working for Independent Senate candidate Anthony Pesec.

It seemed to yield results for two Green candidates who worked their way down Swinden Street in Downer on a recent Saturday. They secured the vote of a man whose dog was called Winston after Churchill.

Another, further down the road, promised to put a Greens sign in the garden. In what is the Greens heartland, only one person said, "I'm not interested." About half were out or hiding behind the curtains.

Candidates invariably say they love door knocking - the chance to discuss problems with real people, etc - but a few volunteers are cagier, particularly with the threat of a barking dog.

They said you just can't tell how a householder will vote by the type of house. Usually.

Greens Senate candidate Dr Penny Kyburz reckons a native garden indicates a sympathiser. Wind chimes? Not a reliable indicator, she thought. Nor a Prius in the drive.

One Liberal volunteer who didn't want his name used thought - uncharitably - that an untidy garden often indicated a Green voter.

Labor senate candidate Katy Gallagher said - also uncharitably - that a "No Junk Mail" sign could indicate a green house. Greens take exception to the wasteful use of pulp from trees. So runs the reasoning.

The Liberal volunteer claimed to have been leafleting alongside volunteers from other parties when a man approached. The Liberal leaned over to the Green canvasser and said: "He's one of yours". She wasn't so sure because he wore a smart suit, but he turned out to be a Green. The bright stripey socks were the giveaway, the Liberal explained.

So went the good-natured banter among the volunteers outside the library in the city centre as early voting began. One Independent offered to buy coffee for the rest - an indication of worker solidarity across party lines.

What volunteers invariably say, though, is that there are no real predictors. People surprise, usually in a good way. The doorknockers said that posh cars and houses can reveal Labor voters. Liberals are welcomed in less affluent homes.

"You try to make a judgment," said the Liberal activist who joined the party four decades ago in his teens. "But half the time, you'd be wrong."

"Most people are reasonably polite but when you get people who don't want to talk, you just get a 'huh'. Very few people are downright rude."

Labor volunteer, Carolyn Kidd, agreed. "People aren't aggressive," she said. She didn't mind disagreement as long as, say, the Liberal whom she had engaged in conversation showed respect.

Independent candidate for the electorate of Canberra Tim Bohm was out on a windy Sunday morning at Dickson shops. "People are seeking me out," he said. "It's not easy but it is enjoyable."

Dr Kyburz, the Green, said, "People are polite - the vast majority of the time." Tim Hollo who is contesting Canberra for the Greens said, "I've never had anyone be aggressive towards me."

They spent a Saturday afternoon padding the streets and knocking the doors, he with his bike, she with her green scarf, green clipboard, green fuzzy earrings and green boots.

By the way, her phone number is a palindrome, the same backward as forward. She is a lecturer in the ANU's Computer Science Department and her mathematical bent pushed her towards the interesting number.

The Greens have been door knocking twice a week from September to November and more as the election has approached.

One Labor team reckoned it had knocked 11,000 doors.

Last Tuesday, one woman welcomed candidate Alicia Payne like a long lost sister. Across the road, though, the man who opened the door in his hoodie gave a brusque brush off before getting in his ute and roaring away. Same street, different attitudes.

Labor has changed its technique. In the past, it used a pair of door knockers per street, each one "leap-frogging" to try every other door. Now, whole teams go down a street with a central director pointing at hopeful houses.

The reasoning is that a bigger team has more fun and so the trek is more attractive to volunteers who might be reluctant.

The Liberals have recently given up on a very sophisticated data-mining system called i360 which harvests information about householders to identify possible Liberal voters.

The parties build up information over elections to try to identify persuadables. It's word-of-mouth and a pencil on paper - Number 11 is against or for - that kind of thing.

More sophisticated data mining where the details of our tastes and views are available is fraught with issues about privacy - and would be invaluable to a seller of anything from goods to political ideas.

The current method is more basic.

And so are the risks - like dogs. Volunteers all seemed to love dogs. Or so they said.

"I can read the body language of dogs," Labor volunteer Robyn Kidd said.