One of the great challenges in conducting any survey research is the possibility of structural bias in the data collection process. One possible bias is that surveys on a particular day of the week may produce different results than some other day.
At ScottRasmussen.com, we recently compared the results of data collected each day of the week and found a reassuring level of consistency.
For all surveys launched on Sunday nights, the president’s Job Approval rating was at 46%. It was 47% for surveys launched on Monday and Wednesday. On Tuesday and Thursday launches it was 48%. For each of those days, we conducted more than 10,000 interviews with registered voters.
We launched a much smaller number of interviews on Friday nights, but the results were also broadly consistent and average a 48% approval rating.
On the Generic Congressional Ballot, the consistency was the same. On average, Democrats led by 6 to 8 percentage points regardless of the day the poll was launched.
ScottRasmussen.com will soon be releasing both the president’s Job Approval ratings and the Generic Congressional Ballot on a daily basis. When we do, we will release results on a three day rolling average basis. This provides even more consistency and continuity than the single day numbers.
See a summary of day by day results.