Ent,
Please allow me to comment on your qn since I'm in the business. Really it's no rocket science to make a hpt, u can think of it like the litmus paper we use in schools, except that it tests for presence of HCG instead of pH levels. I would like to guarantee 100%, but well, things like proper usage (such as using first morning pee esp for very early pregnancy) is not within my control. Still, we probably have more 99% accuracy. [IMG=http://www.singaporemotherhood.com/forumboard/clipart/happy.gif] And I definitely agree with starry that clearblue is expensive because it has to maintain it's brand-name, rather than being any better in terms of accuracy. In fact, if I may secretly whisper to u gals, I think that company is a rip-off, that's one reason why I decided to bring in cheap but good hpts and opks for ladies here!
One reason I can think of for the supposed false positives, is detection of a chemical pregnancy using hpt which is too sensitive, like only 10mIU/ml. That's why I always suggest to ladies to buy tests with at least 20mIU/ml, better to get BFP confirmed a few days later, than to detect a chemical preg early only to get yourself all depressed!
Ok enuf said, so trust your cheapo less-than-a-dollar hpt, so long as u use it properly! [IMG=http://www.singaporemotherhood.com/forumboard/clipart/happy.gif]
Enjoy your evening ladies! I've just reached home, going to have dinner now [IMG=http://www.singaporemotherhood.com/forumboard/clipart/happy.gif]