There are lots of good hyperlinks at the link that are well worth the time to click and read.
This point may be true in a general sense. But Trump has changed the rules and the dynamics of politics as we knew it. I agree with this article that shows polling numbers for Trump may be LESS THAN actual support.
BREAKING: Shocking Report Exposes Secret Behind Trump’s Support… It’s NOT What It Seems
Conservative Tribune ^ | 12/23/2015
Posted on Wednesday, December 23, 2015 9:10:48 AM by BlackFemaleArmyCaptain
Donald Trump has been a front-runner in the 2016 presidential election since he entered the race over the summer, and now new analysis of the polls has suggested that Americans may actually be understating their support for him.
In an analysis conducted by Morning Consult, it was discovered that Trump has done better in online polls than in surveys conducted over the phone.
The study noted: "Trump receives about 5 percentage points more support among registered Republicans and Republican-leaning Independents online compared with live telephone interviews."
The firm's polling director, Kyle Dropp, spoke with the Los Angeles Times and explained why Trump's support may appear higher in online polls and why the online polls are more accurate.
Dropp noted that many of Trump's supporters, especially those with college educations, are "less likely to say that they support him when they're talking to a live human" than when they are in the "anonymous environment."
In fact, the study showed that adults answering questions about Trump on the phone were more likely to hide their opinion from the surveyor because of "a social desirability bias in which respondents answer questions in a manner they believe will be viewed favorably by others."
On the other hand, blue-collar Republicans answered the same regardless of the method.
The study was widespread. Some 2,397 potential Republican voters were polled in early December, either by telephone survey, an online survey or by an interactive dialing technique.
Dropp said that the results of the experiment were clear.
"Voters are about 6 points more likely to support Trump when they're taking the poll online then when they're talking to a live interviewer," he said.
While Trump continues to lead in the Republican Party primary, voters may be surprised by Trump's overwhelming number of supporters.
(Excerpt) Read more at conservativetribune.com ...
Yes. I look at the Des Moines Register polls and other local Iowa polls that show Ted Cruz is favored to win the Iowa caucus. That flies in the face of national polls that show Trump is leading. But I won't be surprised if Cruz wins Iowa.