Imagine an empty graph with an x and y axis. Imagine quality of life is on the y axis and amount of additional life is on the x (horizontal). If you add a year of life at perfect health, that’s a tall rectangle like a skyscraper. If you add lots of years of life at low quality (maybe with high pain), then that’s a long but low rectangle. The area of each rectangle is the number of QALYs. You can imagine many differently shaped rectangles can have the same area. Does that imagine help?
Imagine an empty graph with an x and y axis. Imagine quality of life is on the y axis and amount of additional life is on the x (horizontal). If you add a year of life at perfect health, that’s a tall rectangle like a skyscraper. If you add lots of years of life at low quality (maybe with high pain), then that’s a long but low rectangle. The area of each rectangle is the number of QALYs. You can imagine many differently shaped rectangles can have the same area. Does that imagine help?