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Comment by ehsankia | Hacker News Reader

> I assumed confidence to be the probability of each task. However, often they do not add up to 100. If they do not represent probabilities what do they represent?

The probability of each being true independently?

> How can Google possibly predict activity type between IN_TWO_WHEELER_VEHICLE vs IN_FOUR_WHEELER_VEHICLE ?!

Two wheel vehicles can often make it through traffic, in between cars.

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Measuring how much the phone rolled back and forth could be a factor, too. You don’t have to keep a car balanced, you do have to keep a bike/scooter/motorcycle balanced.

> How can Google possibly predict activity type between IN_TWO_WHEELER_VEHICLE vs IN_FOUR_WHEELER_VEHICLE ?!

Could they be using this from accelerometer data instead of GPS? https://github.com/guillaume-chevalier/LSTM-Human-Activity-R...

https://news.ycombinator.com/item?id=13049143

I drive a motorcycle in Thailand all the time google is more wrong than right when predicting this.

I'm gonna bet that Thai bike-driving habits are different from those of people in the US, at least in cities.

I going to bet there are more bike driving people with Android phones in places like Thailand, Indonesia, India and the Philippines where on-road behavior is more similar to each other than to the US.

I think it's a pretty hard problem, and we shouldn't be surprised if the accuracy there is low.

https://developers.google.com/android/reference/com/google/a...

It's probably a combination of features, but the suspensions are different, and two wheelers lean when they turn, which should be easy to distinguish from the accelerometer and gyros.

Seems feasible to detect a user at above foot speed,that appears to be stopping at intersections but seems to be more immune to congestion than others and label it as a two wheeled vehicle.

There are also certain roads/paths that are bike only, through convention (bike lanes) or physical width restrictions.

LOL. There are no such paths in India - Article Author

I've never been to India but presumably you have some parks... However, I do see that google maps has the bicycle overlay greyed out for New Delhi!

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