Hillary made 10000% returns over 10 months while the average senator makes 125% return over a year. 125% is still high but it's on a very different scale than the returns that Hillary made on the cattle-futures.

If you want to explain 125% returns than you can explain it with knowledge of upcoming legislation and those four factors.

On the other hand those factors don't make sense to explain how someone made 10000% returns by buying shorts when the market doubled over 10 months.

The statistical evidence is the study by Ziobrowski, Cheng, Boyd, and Ziobrowski of the stock portfolios of US Senators. They found that stocks held by Senators outperformed the market, with both purchase and sale significant events.

That sentence omits the interesting information that the senators underperformed the market in their sale decisions. That basically means the buying decision is often based on insider information and once most but not all of that information is priced in the senator sells the stock.