Once you see that an answer is not serving its question properly anymore, it should be tossed away. It's just their natural life cycle.
They usually kick and scream, raising one hell of a ruckus when we ask them to leave. Especially when they have been with us for a long time.
You see, too many actions have been based on those answers. Too much work and energy invested on them. They feel so important, so full of themselves. They will answer to no one. Not even to their initial question!
The hardest thing about customer interviews is knowing where to dig. An effective interview is more like a friendly interrogation. We don’t want to learn what customers think about the product, or what they like or dislike — we want to know what happened and how they chose... To get those answers we can’t just ask surface questions, we have to keep digging back behind the answers to find out what really happened.
Keep your contact information in a prominent location.
Write for yourself and for posterity.
Write pertinent field information with every new entry. You should enter the date, time, and location at the top of every page.
Add information on your location.
Record your methods.
Make backup copies.
If you use abbreviations, make sure there is a key in your field notebook.
Don’t leave home without it.
Form a writing habit. Thomas Jefferson was such an inveterate chronicler of daily events in his notebooks that he even took the time to record the weather four times on the day he helped write the Declaration of Independence. So unless you have something far more pressing than writing the Declaration of Independence, you have no excuse for avoiding your field notebook!
Set up a structure for your field notebook.
Create an index.
Treat your field notebook like a scrapbook. You should view your field notebook as a central clearinghouse for miscellaneous information that is relevant to your research project. If there are related bits of information that you will find useful later on, sketch them, write them down, photocopy them, and staple or tape them in your notebook.