Speed Checkers

On checking my BB Speeds with several of the websites I consistently get indicated download speeds of approx 60% less when using ThinkBroadband checker. For example BB Speedchecker indicates the following results on tests performed over the last few hours 31MBPS,34, 33,34,32,34 against 14,19,23,15,13,22MBPS ThinkbroadBand. Furthermore Speedtest Net shows 32,30,33,29 30, 28MBPS, Broadband Choices 29,30, 31,32,31,30.
These tests were all done together. Which one is correct?. I am running newly installed BT Infinity.

The second paragraph of this reply on another thread earlier today may be of help.

As they're essentially measuring things in different ways the results are different.

As well as what cheshire_man and that links say, those other checkers use the same test as each other, (Ookla), and do just what the link says.

If you are running Kaspersky or Avira then Ookla is totally unreliable. You would need to enable Windows firewall and disable your IS. That's worth a try anyway.

Thanks for your reply. I am not complaining at my speed increase as it was usually between 2.5mbps and 5.5mbps and downloads are significantly faster. I was just commenting on the substantial discrepancy between ThinkBroadband and all the others. The Openreach engineer speed test indicated +30mbps after the installation was up and running.He said that that was what he expected bearing in mind the distance from the cabinet.
I am not running Kaspersky or Ovira. My Windows 7 firewall is set.
The speed test will not run the Java required by the ThinkBroadband tester when using Namoroka 64 bit. I have to use the 32 bit version.Another strange anomaly!