Methodology

AAPOR TI_CharterMember

The Rutgers-Eagleton Poll conducts statewide telephone surveys of the New Jersey adult and New Jersey registered voter populations with a scientifically selected random sample using a random-digit-dialing (RDD) method. Respondents within a household are selected by asking randomly for the youngest adult male or female current available (18 or older). If the named gender is not available, the youngest adult of the other gender is interviewed. The poll is available in Spanish for respondents who requested to do it in that language.

In each New Jersey statewide poll, our goal is to reach at least 30% of our respondents on cell phones, to best reflect the estimated cell phone-only household rate of 19.4% in New Jersey (CDC estimates 2012). This number will increase depending on details of a specific poll and as over time the number of cell phone only households increases. All Rutgers-Eagleton polls are conducted using live interviewers.

Data are weighted to the demographics of adults in New Jersey. Weights account for the probability of being selected within the sample frame and the probability of being sampled within a household, based on the number of individuals living in the household and the phone composition (cell, landline) of the household. The samples were weighted to several demographic variables reflecting the population parameters of the state of New Jersey: gender, race, age, and Hispanic ethnicity. The final weight, which combined all of the parameters mentioned, was trimmed at the 5th and 95th percentile so as to not accord too much weight to any one case or subset of cases. All results are reported with these weighted data.

All surveys are subject to sampling error, which is the expected probable difference between interviewing everyone in a population versus a scientific sampling drawn from that population. Sampling error should be adjusted to recognize the effect of weighting the data to better match the population. Thus if our simple sampling error is +/- 3.6 percentage points and 50 percent of New Jersey registered voters favored a particular position, one would be 95 percent sure that the true figure is between 46.4 and 53.6 percent (50 +/-3.6) if all New Jersey registered voters were interviewed, rather than just a sample. We also account for the design effects of our samples and report an adjusted margin of error that reflects these design effects.

Sampling error increases as the sample size decreases, so statements based on various population subgroups are subject to more error than are statements based on the total sample. Sampling error does not take into account other sources of variation inherent in public opinion studies, such as non-response, question wording or context effects.

The Rutgers-Eagleton Poll is generally fielded by the Eagleton Center for Public Interest Polling. The questionnaire is developed and all data analyses are completed in house. The Rutgers-Eagleton Poll is paid for and sponsored by the Eagleton Institute of Politics, Rutgers University, a non-partisan academic center for the study of politics and the political process. Full questionnaires are available on request, and can also be accessed at the Eagleton Poll archive at www.eagletonpoll.rutgers.edu. Please see individual press releases for more specific details, or for more information, please contact eagleton.poll@rutgers.edu.

 

To learn more about the AAPOR Transparency Initiative, see here.