About this lesson
Problem solving often requires an interim solution while a permanent solution is being developed and validated. When multiple possible solutions are available, the team should recommend a solution approach.
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Quick reference
Problem Improvement
Problem solving often requires an interim solution while a permanent solution is being developed and validated. When multiple possible solutions are available, the team should recommend a solution approach.
When to use
Determining the solution approach is the first step in the Improve phase of the Lean Six Sigma project. Depending upon the nature of the problem, an interim solution may be needed in addition to a permanent solution. Also, there may be multiple possible solutions and the team must decide on the solution path that will be followed.
Instructions
When determining a solution approach for a Lean Six Sigma project, there are three key questions that must be answered.
Interim – Permanent
The first question concerns the need for an interim solution. Based upon the urgency or severity of the problem, some problems will require an interim solution. This interim solution is normally focused on addressing the immediate problem. It will isolate and quarantine the immediate problem, possibly conducting a recall of released items. These will need to be repaired or replaced.
While this addresses the immediate issue, it does not prevent the problem from recurring. A permanent preventive solution is needed to do that. When the permanent solution is put in place, elements of the interim solution – such as special screening tests – should be removed. If the problem is relatively minor or the impact is one that the business and customers are already attuned to, an interim solution will not be required and the team should immediately start working on the permanent solution.
Solution Path
Depending upon the nature of the problem and potential solutions, there are three solution paths open to the Lean Six Sigma team.
Single viable solution – When there is only one viable solution to the problem, don’t agonize over it, just implement it.
Mutually exclusive solutions – Multiple solutions are possible, but once a path is chosen, the other alternatives are no longer viable. In this case evaluate all the options for both technical efficacy and the ability of the organization to implement the solution. Select the best solution and reject the others.
Multiple complementary solutions – Multiple solutions are possible and they can be implemented independent of each other. Each solution provides some benefit and in combination they are even stronger than by themselves. In this case, prioritize the solution based upon their cost and impact and implement as many as the organization can afford, or until the project performance goals have been reached.
Solution Selection Matrix
To prioritize or select a solution among solution options as described in paths 2 and 3 above, a tool is needed to support the analysis. The solution selection matrix is the most commonly used tool. This matrix has many variations and names, but all of these variations follow the same general approach. A set of criteria for evaluating the options are selected – normally by the stakeholders. These criteria may also be weighted based upon which is most important to the stakeholders. I prefer to use a weighting scale of 15 where 5 is for criteria that are critical to success and 1 is for nice to have, but not essential.
Each of the solutions are evaluated using a simple numerical scale. I prefer the scale of 1 to 9 but there are many scales in use. The option that fully meets or exceeds the expectations of the criteria is scored a 9 and the option that badly misses is a 1. Once each solution option has been scored against each criterion, the scores are multiplied by the weighting factors and a composite solution score is calculated by summing the criteria scores. The solution with the highest score is the best solution option. In the example below, Solution B has the best technical performance, but Solution A has the best overall score because it's faster to implement, least expensive and is aligned with the organization’s strategic goals.
Solution Approach 
Factor 
Technical Performance 
Org Goal Alignment 
Cost to Implement 
Time to Implement 
Total Score 
Weight 
5 
4 
2 
3 

Solution A 
6 
9 
7 
8 
104 

Solution B 
8 
5 
3 
4 
78 

Solution C 
4 
6 
5 
5 
69 
Hints & tips
 You may need to initiate an interim solution before you have completed the Measure or Analyze phases. This is often needed if there is a health or safety risk to the problem.
 If you have to follow solution path 2 – choosing between mutually exclusive options – engage your stakeholders in the decision process.
 The weights for the decision criteria in the solution selection matrix should be established by the stakeholders, not the project team. The stakeholders will have to live with the result, the project is disbanded or goes on to the next project.
 There are lots of different weighting scales and scoring scales. In virtually every case they will give you the same ranking of solutions, so don’t agonize over the scales. Pick one, or use the one you are directed to use and do the matrix.
 The solution selection matrix is not so precise that differences in the solution scores of a few percent are not significant. If in the example above, Solution A scored 104 and Solution B was 101, I would say that as far as this analysis is concerned, their scores are equal.
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