does a thesis statement need supporting evidence

Example: I feel that good hygiene begins with the basics of effective hand-washing.

Example 5: George Will writes, “Economic equality is good for the United States.”

What you plan to argue + How you plan to argue it = Thesis
Specific Topic+ Attitude/Angle/Argument=Thesis
The best thesis statement is a balance of specific details and concise language. Your goal is to articulate an argument in detail without burdening the reader with too much information.

Statement of fact: “A candidates ability to afford television advertising can have an impact on the outcome of Congressional elections.” This is essentially an indisputable point and therefore, not a thesis statement.
In conclusion, your thesis should make clear what your argument is; it should also provide the reader with some indication of why your argument is persuasive.

SOME OPENING STRATEGIES
4. Qualifications — Those acknowledgements which make your claim and evidence more precise

Spain’s neutrality in WWII occurred for an entirely personal reason: Franco’s desire to preserve his own (and Spain’s) power.

As you work on your thesis, remember to keep the rest of your paper in mind at all times. Sometimes your thesis needs to evolve as you develop new insights, find new evidence, or take a different approach to your topic.

References:

http://courses.lumenlearning.com/suny-englishcomp1v2/chapter/effective-thesis-statements/
http://depts.washington.edu/pswrite/thesisstmt.html
http://sociology.morrisville.edu/perpetual/Writing/Thesis-statement-guidelines.htm
http://writing.wisc.edu/handbook/process/thesis/
http://saylordotorg.github.io/text_handbook-for-writers/s10-03-supporting-a-thesis.html