Why you shouldn't make a meal of four-star food reviews

Here's why you can never trust an online food review – we're way too positive about the food we eat.

In fact, we over-rate our own food experiences so much that restaurant review services have to tone us down.

That's the remarkable conclusion drawn from millions of online reviews for Australia's cafes, restaurants and bars.

It's why top online food reviewer Louisa Wright reckons her average rating is three stars – but her own data actually reveals more than 75 per cent of her restaurant reviews are four stars or above.

"Maybe it's the places I'm choosing to go to, I have not been disappointed by those places," she told Fairfax.

"Maybe you look for the positives as well."

"Why do people do it? Simple. People like to please," says CSIRO social scientist Dr Zoe Leviston.

On Zomato (formerly known as Urban Spoon), almost 70 per cent of new users start with a four or five-star review.

On Yelp 44 per cent of all reviews – of all reviews – are five out of five.

We are so delighted with our food choices that Yelp and Zomato have to create sophisticated algorithms to try to compensate.

Zomato, for example, puts every restaurant in Melbourne on a grading curve, ensuring that restaurant ratings are relative.

Think of it like this: if ratings weren't adjusted, nearly every restaurant in Melbourne would be getting rave reviews.

Why are we so positive in food reviews?

It's called acquiescence bias, Dr Leviston says – "the tendency for people to agree with a proposition rather than disagree with it".

It manifests in all sorts of social research; basically, wherever people are asked to rate things, a strong bias exists toward a positive rating.

Even more interesting: restaurants typically get rave reviews straight after opening, then lame reviews as a sort of push-back effect.

It's only after a few months that ratings start to level out. Zomato's data suggests this is a trend that affects many new buzz openings.

That happened to Matcha, St Kilda's biggest new opening since ... Well, the Stokehouse isn't open yet is it?

Matcha is built for buzz; it's vegan, it's food looks great on Instagram, it's owners are very social-media savvy.

But it's ratings on Zomato have been odd, to say the least.

"Initially Matcha Mylkbar had raving reviews of fours and fives within their first month of opening," a Zomato spokeswoman said.

"As their hype subsided reviews began to hover around 1.5 - 2.5. Recent reviews see the restaurant averaging a 2.5 rating and a 2.8 overall".

Nic Davidson, one of Matcha's co-owners, thinks the restaurants own buzz might be contributing.

The cafe has proved so popular since it opened that people are now having to line up for quite some time to get a table.

"Because people sit there for two hours, they sit down and sometimes they are angry already.

"We cannot change that – it's not our fault you waited."