Trump in Dead Heats With Biden and Sanders, Half of Voters "Silently" Support Trump
Zogby Analytics conducted an online survey of 897 likely voters in the US 8/9/19 – 8/12/19.
Using internal and trusted interactive partner resources, thousands of adults were randomly invited to participate in this interactive survey. Each invitation is password coded and secure so that one respondent can only access the survey one time.
Using information based on census data, voter registration figures, CIA fact books and exit polls, we use complex weighting techniques to best represent the demographics of the population being surveyed. Weighted variables may include age, race, gender, region, party, education, and religion.
Based on a confidence interval of 95%, the margin of error for 897 is +/- 3.3 percentage points. This means that all other things being equal, the identical survey repeated will have results within the margin of error 95 times out of 100.
Subsets of the data have a larger margin of error than the whole data set. As a rule we do not rely on the validity of very small subsets of the data especially sets smaller than 50-75 respondents. At that subset we can make estimations based on the data, but in these cases the data is more qualitative than quantitative.
Additional factors can create error, such as question wording and question order.