Pain is subjective; it is whatever the person experiencing it says it is. But to effectively treat pain, it helps to quantify it, which is why medicine came up with pain scales.
Learn more about advertising on the HowStuffWorks podcasts at www.howstuffworks.com/advertisers.htm
And to learn about your ad choices when listening to podcasts, visit
https://www.howstuffworks.com/privacy.htm#ad-choices