The Social Security Advisory Board has issued a 130 page document titled Aspects of Disability: Decision Making: Data and Materials. It is filled with charts which one can use to make many different points. I'll post several but let's start out with this one. You can make a lot of different points based just upon this chart alone but one you cannot easily make is that it has become less difficult to get on Social Security disability benefits in recent years. Hearing allowance rates went up slightly but only because allowance rates went down at lower levels. Recently, all allowance rates have gone down a bit.
The difference at the hearing level between dispositions and decisions is the cases dismissed for technical reasons such as filing the request for hearing too late or failing to appear for a hearing.