Categories of problems

There are three categories of problems. ‘A’ Problems: Cause is known; these problems are often related to non-conformance or no standard work; 60-70% of the problems are fall into this category. ‘B’ Problems: Cause is known; these problems are normally solved using the A3 methodology; approx.. 20% of problems are in ‘B’ category. ‘C’ Problems: Cause is unknown; require an A3 and deeper analyses using tools like cause and effect diagrams and ‘5 Why?’ analyses; 10% of the problem are fall into this category.