November 2014 Winthrop Poll of Adults in SC
The November 2014 Winthrop Poll
interviewed 852 adults living in South Carolina. After weights (for sex,
age, and race) have been applied, results which use all respondents have a margin
of error of approximately +/- 3.4% at the 95% confidence level. Results
that use less than the full sample will naturally have a higher margin of
error. 40% of the respondents came from wireless (i.e. cell phone) sample.
The survey was in the field from 11/9-11/16, 2014. Phone calls were made during
weekday evenings, all day Saturday, and Sunday afternoon and evening. Weekday
daytime calls are not made to avoid oversampling those who are more likely to
be at home during the day (e.g. retirees, stay-at-home-moms, etc.). Conducting
weekend calls is important to avoid systematically excluding certain
populations (such as those who may work 2nd or 3rd shift during the week).
The survey used (1) Random Digit Dialing (RDD) and (2) wireless phone number
sampling. Both RDD and wireless samples are crucial to ensure no adult in the
geographical area of interest is systematically excluded from the sample. Both
the RDD sample and the wireless sample were purchased from Survey Sampling
International (SSI). A further explanation of RDD methodology, with
descriptions taken from SSI’s website, may be found below.
Phone numbers selected for the survey
were re-dialed five or more times in an attempt to reach a respondent. Once a
household was reached, we also employed procedures to randomize within
households for RDD sample.
1. Weight responses based on sex,
age, and race according to the known population of residents of
SC age 18 and older.
2. Randomize within household for respondents reached via RDD sample
Computerized autodialers were not
used in order to ensure the survey of wireless phones complied with the
Telephone Consumers Protection Act and all FCC rules regarding contacting
The Winthrop Poll is paid for by
Winthrop University with additional support from The West Forum on Politics and
Policy at Winthrop University.
Additional Explanation of RDD
Methodology : (with descriptions taken from SSI website)
Samples are generated using a
database of "working blocks." A block (also known as a 100-bank or a
bank) is a set of 100 contiguous numbers identified by the first two digits of
the last four digits of a telephone number. For example, in the telephone
number 203-567-7200, "72" is the block. A block is termed to be
working if some specified number of listed telephone numbers are found in that
of random numbers distributed across all eligible blocks in proportion to their
density of listed telephone households are selected. All blocks within a county
are organized in ascending order by area code, exchange, and block number. Once
the quota has been allocated to all counties in the frame, a sampling interval
is calculated by summing the number of listed residential numbers in eligible
blocks within the county and dividing that sum by the number of sampling points
assigned to the county. From a random start between zero and the sampling
interval, blocks are systematically selected in proportion to their density of
listed households. Once a block has been selected, a two-digit number is
systematically selected in the range 00-99 and is appended to the exchange and
block to form a 10-digit telephone number.