Polling data is just another kind of statistic that is routinely used to bolster or attack a candidate's campaign. We Americans are a fickle people. We reserve the right to change our minds. That said, while single polls (or even multiple polls taken around the same time) don't tell us much but the current mood, longitudinal trends in poll results say a lot.
If I say that Johnny got a C on the test and Eddie got a D, you might assume that Johnny is doing better in the class. However, if Johnny's grades were steadily declining from A's to B's to C's, while Eddie's grades were moving from low F's to the middle of the D range, the picture becomes clearer. If both students continue in their current paths, Eddie will soon be getting higher test scores than Johnny.
This is what is occurring with the election polls. Let's sum up the statistics with a bit more analysis:
Hillary Clinton's Favorability Rating -
May 17, 2016
Favorable - 41.1%, Unfavorable - 54.8% -- 13.7% Net Unfavorable Rating
April 3, 2016
Favorable - 41.6%, Unfavorable - 54.2% -- 12.6% Net Unfavorable Rating
Donald Trump's Favorability Rating -
May 17, 2016
Favorable - 38.6%, Unfavorable - 57.8% -- 19.2% Net Unfavorable Rating
April 3, 2016
Favorable - 31.6%, Unfavorable - 63.0% -- 31.4% Net Unfavorable Rating
What's the scoop?
When you analyze the data in context, Donald Trump's ratings have improved dramatically, improving the net favorable/unfavorable gap by 12.2%. We can also see that his favorability ratings are very malleable. He has more of an ability to change his pubic perception than does Hillary Clinton, whose trend lines are very stable.
Hillary Clinton's ratings have dropped steadily since March of 2015, when her favorable and unfavorable ratings were equal. Her favorables have dropped at almost the same rate at which her unfavorables have increased. From April 3 to May 17 of 2016, her ratings have worsened slightly but steadily, broadening the gap by 1.1%. Her numbers have trended very steadily in the same direction for over a year now, meaning that changing her public perception will be very difficult for her.
If the current trends continue, by November 2016 Donald Trump will have an overall favorable poll rating and Hillary Clinton will have a negative rating of almost 60%. Of course, anything could happen in the meantime.
The daily snapshots tell a very limited story. As they say, there are lies, there are damn lies, and there are statistics. Look at the direction in which poll results are heading. The wind is blowing in Trump's direction.
(All poll data derived from the Huffington Post Poll Chart for Donald Trump and for Hillary Clinton. Data is accurate as of 3:00 pm Eastern time, May 17, 2016. Check the links to see if and how it has changed.)