How to read a poll (these days)

The poll in question

This is a tracking poll, and I think it will be updated each day, so the exact numbers will change.  I'll doing it with the numbers I have right now. 

Stated result
Hillary 44.1, Trump 41.6, the rest/undecided 14.3

Step 1) the true part

Among democrats
Hillary 86, Trump 6, the rest/undecided 8
Among republicans
Hillary 6, Trump 84, the rest/undecided 11
Among independents polled
Hillary 33, Trump 43, the rest/undecided 23

Of the rest, Johnson leads Stein about 2.5:1



Party identification breakdown:(Unweighted) 335 Democrats/375 Republicans/312 Independents; (Weighted) 379/311/322. Results in table above are based on weighted sample. 

Did you catch that?  Despite probably trying to poll more democrats, they ended up with more republicans, and ended up "weighing" the data to count the democrat votes more.  That's what weighing means.  There is no explanation for why they chose this weighing.

So the ACTUAL poll results (unweighted)

Party	Votes	For Clinton	For Trump	Other
Democrat	335	288	20	27
Republican	375	23	315	38
Independent	312	106	137	69
Total	1022	417	472	133
as a percent	100	40.8	46.2	13.0

This is a 5.4% lead for Trump.  
If you weigh to the actual party affiliations in the country:
 

Party	Votes	For Clinton	For Trump	Other
Democrat	307	264	18	25
Republican	266	16	223	27
Independent	449	153	198	99
Total	1022	433	439	150
as a percent	100	42.3	43.0	14.7

Then when you factor in enthusiasm (likelihood to vote) you probably end up closer to the first poll.  So a Clinton +4 is actually a win for Trump.