Americans did not choose Harriet Tubman to be on the $20 bill.
First of all, the poll that this conclusion was derived from didn't even offer an option for "retain Andrew Jackson." The poll literally only asked which female would be preferred.
Second of all, the study is already bunk at the start because it's an elective survey. People already know what the topic is when they decide whether or not to take it. This means that people who don't really care are likely to just close the window, and the results will just be people who have strong opinions on it. This skews the results because only outliers are in the results.
So, the conclusion should be as follows: Participants in the Women on 20s Survey Prefer Harriet Tubman Over Other Females to Put on the $20 Bill.