This has probably been asked before...I have just started the Persona (now month 2) and this month, the persona came up with 2 days ovulation (on day 9 and 10). At the same time, this month I decided to try the digital ovulation tester (as I was told it could take at least 3 months to find out when you ovulate with the persona) and from day 8 until day 15, I have a smiley face (which means due to ovulate..?). I thought it would only have a smiley face for a couple of days... why has it done it for the whole 7 days? I assume Persona is more accurate?
bozzy i was using both persona and OPKs for first month of ttc'ing after a m/c - and like you, got 2 0 days on persona - i only did the OPK over about 3 days before and got all negs until same day as persona got the smiley face. i then didnt bother with anymore OPKs as they seemed to be in agreement - ie. that i would be ovulating in the next 48 hours.
Åm afraid i cant give you any kind of definitive answer as i'm still sussing it out myself, but as far as i can tell they should really match up because they are both measuring your Luteinizing hormone surge.