How many mistakes you should tolerate
A good, old saying goes "If you never made a mistake, you probably ain't to anything." And that's right. We all make mistakes and they happen on all levels, from the very top to the floor. Some are big, some are small, some are catastrophic, but they happen.
We believe that you already know that you should focus on the problem itself, not on a person, but when you solve the problem and correct the mistake, what to do with the employee/s that caused it? And the most important question is: what if the same person is repeating mistakes?
One of the possible solutions is to calculate the relative damage the mistake caused to your business. If the sum is large enough to jeopardize your company financially, fire that person. If the damage can be repaired with relatively small amount of money, talk to him and see what are the reasons behind the mistake.
Now, if the damage is hard to be expressed in money - let's say it is damaging the brand reputation - try to estimate how big the problem at hand is. But be very careful: it is very easy to overestimate the damage to the brand because we all think our company should be spotless and it's easy to fire an employee for a reason that's minor. Only your experience can tell is your brand in real danger or it's one of those "The dogs bark, but the caravan goes on" situation.
A loud protest from your customers doesn't mean you should jump right away and fire people right away. Stop and think, estimate the situation and then decide.
OK, everything's fine and well, but what about a person that makes more mistakes than other workers? You may use the same principle again: sum all damages together and see what you got. If the number is substantial, fire. If it's not, talk. And in any case, try to find real reasons behind mistakes because they are an excellent way to learn a lot about your company and your people.
Be guided by this saying: "Successful products are children of failures." How? It's simple: To make a good product, you need experience. To get experience, you have to survive failures along the way. Thus, you are making good products thanks to your failures. Think about that before you fire somebody.