Guidance and brochures have a correlation coefficient of 0.17 and an evaluation average of 2.6; the evaluation average is indeed low, but the correlation coefficient is below 0.5, so it lies in the lower-left region where the relationship with the overall evaluation is weak. An item with a weak relationship has little ripple effect on the overall evaluation even if improved, and a poor return on investment, so it does not become the highest-priority improvement target. The description of the region is correct, but the conclusion that it should be improved with the highest priority is wrong.
×Incorrectイ
Technique and finish quality have a correlation coefficient of 0.31 and an evaluation average of 3.4. That the evaluation average is high (above 3.0) is correct, but the correlation coefficient is below 0.5, so its relationship with the overall evaluation is not strong but weak, and it actually lies in the upper-left region. The choice mistakes the region, claiming it is in the region with a strong relationship, which does not match the values in Figures 1 and 3, so it is wrong.
×Incorrectウ
Customer service has a correlation coefficient of 0.72 and an evaluation average of 3.7. That the evaluation average is high is correct, but the correlation coefficient exceeds 0.5, so its relationship with the overall evaluation is not weak but strong, and it actually lies in the upper-right region. The choice misidentifies the region as the region with a weak relationship, so it is wrong. (Incidentally, the conclusion that the upper-right region, with high satisfaction, is fine to leave as is, is itself valid, but the premise of the region judgment is mistaken.)
○エ
正解In Figure 3, the horizontal axis is the correlation coefficient (the strength of influence on the overall evaluation) and the vertical axis is the evaluation average (current satisfaction); reference lines at a correlation coefficient of 0.5 and an evaluation average of 3.0 divide the graph into four regions. The store has a correlation coefficient of 0.60 (greater than 0.5, so its relationship with the overall evaluation is strong) and an evaluation average of 2.8 (less than 3.0, so current satisfaction is low), so it lies in the lower right of the graph, that is, the region of strong influence and low satisfaction. The stronger an item's influence, the greater the boost to the overall evaluation that improving it brings; and the lower the satisfaction with an item, the more room there is for improvement. The store, which meets both conditions, is the improvement target that can most effectively raise overall satisfaction, and should be improved with the highest priority. Therefore エ is appropriate.
ここがポイント
Portfolio analysis of improvement priority (priority matrix): judge using four quadrants with the horizontal axis = degree of influence on the overall evaluation (correlation coefficient) and the vertical axis = current satisfaction (evaluation average); the lower-right region, with strong influence and low satisfaction, is the highest-priority improvement target.
The correlation coefficient is a value between 0 and 1 that expresses the strength of the relationship (degree of influence) with the overall evaluation; if it is greater than the reference line of 0.5, the influence is strong. An item with a weak relationship has a small improvement effect even if satisfaction is low, so its priority is low.