To break confirmation bias, you need an objective log. Write down every time you recognize a confirming event, as well as every time you recognize an even which is nonconfirming. Then, estimate the likelihood that you would recognize and write down a confirming event, and the likelihood that you would recognize and write down a nonconforming event. Use your surprise that a nonconfirming event just occurred, as well as your surprise that you noticed it and made a note of it to form that estimate.
If you find yourself more surprised that you made a not of a nonconfirming event than that it happened, it probably happens much more often than you note it.
To break confirmation bias, you need an objective log. Write down every time you recognize a confirming event, as well as every time you recognize an even which is nonconfirming. Then, estimate the likelihood that you would recognize and write down a confirming event, and the likelihood that you would recognize and write down a nonconforming event. Use your surprise that a nonconfirming event just occurred, as well as your surprise that you noticed it and made a note of it to form that estimate.
If you find yourself more surprised that you made a not of a nonconfirming event than that it happened, it probably happens much more often than you note it.