Add the word      

                           statistics       

to any keyword search and then add the following site and filetype tricks.  For example:

                 traffic accidents statistics site:.gov filetype:pdf

Remember, no space between the colons, and don't forget the period before  gov  or edu

If you want ONLY results from a government site, end your keyword search with      site:.gov

If you want ONLY results from an educational site, end your keyword search with    site:.edu

(Note: no spaces between colons and be sure to include the  period after the colon)

                   Example:    homelessness mental health site:.gov

******

To get ONLY results with pdfs, end your keyword search with       filetype:pdf

To get ONLY results with powerpoints, end your keyword search with      filetype:ppt

(Note: no spaces between colon, and do NOT include the period for filetype)

                  Example:  homelessness mental health filetype:pdf

******

You also can powerfully COMBINE these limiters and get some really targeted results.

for example :     homelessness mental health site:.edu filetype:ppt         

                          this will will give you ppts from education sites

or: 

 you can search any publicly shared Google Slides presentations by using the search term "site:docs.google.com/presentation/". Docs and Sheets are similar, using "site:docs.google.com" and "site:docs.google.com/spreadsheets/" respectively.

or :                    homelessness mental health   site:.gov filetype:pdf      

                          this will drill deep into  government information