Classifieds and distances
Classifieds and distances
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Original Poster:

18,451 posts

223 months

Sunday 29th May 2011
quotequote all
I'm browsing the classifieds - having entered the first part of my postcode - and spot a nice little motor for sale only 94 miles away.

"Dyfed," I read. Where in Wales is that? A quick check of GoogleMaps answers that question. Although it also tells me it's 155 miles away.

yikes

A few miles difference I could understand, but more than 60?! Not sure what you use to calculate the distances, but it doesn't seem to be especially accurate.

Any thoughts?

marshalla

15,902 posts

230 months

Sunday 29th May 2011
quotequote all
Postcodes cover a large area - especially if you only use the first half of them.

harryowl

1,114 posts

210 months

Sunday 29th May 2011
quotequote all
wont ph be giving a straight distnace and googlemaps calculating actual driving distance?

Pints

Original Poster:

18,451 posts

223 months

Monday 30th May 2011
quotequote all
harryowl said:
wont ph be giving a straight distnace and googlemaps calculating actual driving distance?
I suppose this is likely, but I'd have thought a better algorithm could have been used.

Stuart

11,639 posts

280 months

Monday 30th May 2011
quotequote all
AFAIK we just give an "as the crow flies" distance. It's far from perfect, but it's hard to do much more.

miniman

30,038 posts

291 months

Monday 30th May 2011
quotequote all
Stuart said:
AFAIK we just give an "as the crow flies" distance. It's far from perfect, but it's hard to do much more.
The Google Maps API will let you calculate driving distances, but not sure what the issues might be around the sheer volume of requests that PH would make.

Stuart

11,639 posts

280 months

Monday 30th May 2011
quotequote all
miniman said:
not sure what the issues might be around the sheer volume of requests that PH would make.
That and the commercials of so many requests. Sorry - was in a hurry to get my girl her bottle earlier.

RacingPete

9,197 posts

233 months

Tuesday 31st May 2011
quotequote all
Pints said:
I suppose this is likely, but I'd have thought a better algorithm could have been used.
To give a more technical answer.

We are using the first part of postcodes to work out distances and not the full postcode. There are many reasons why we are doing that, but the consequence is that we use the central point for that first part of the postcode.

This means that in large catchment areas you could live on the furthest side of the postcode region, looking at a car on the furthest side away from the postcode the seller is in. This equates for some big distance gaps.

The system also uses an as the crow flies calculator, so doesn't account for road travel. Creating more accurate distance calculators cost money and time, so indicative is the best we can do for now - but we are working on how we can improve this for the future, so watch this space.

Pints

Original Poster:

18,451 posts

223 months

Wednesday 1st June 2011
quotequote all
Thanks, Pete. I'm sure it's the "crow flies" method causing the large variance, since I also usually only use the postcode area in my googlemap searches rather than exact/full postcodes.

There are some other classified related questions I have on the back of suggestions I've had from colleagues - I always suggest PH Sales as the 1st port of call when they're looking for replacement motors angel - but that can wait til I'm not posting from my mobile.