Nonresponse Bias in a Dual Frame Sample of Cell and Landline Numbers

We conducted a dual frame survey of landline and cell phonenumbers in 2004 to evaluate the feasibility of including cellphone numbers in random digit dial telephone surveys in theUnited States. By sampling cell phone numbers, the coveragebias associated with households that have only cell phones iseliminated. However, we discovered two major sources of nonresponsebias in the dual frame sample. In an attempt to reduce thesebiases, we applied several different estimation schemes. Buta comparison to the 2004 Current Population Survey Cell PhoneSupplement showed that none of the estimation schemes substantiallyreduced the nonresponse bias of the estimates. We suggest othermethods that might be used in future surveys that include cellphones and discuss the need for additional data collection andresearch on this issue.     

The State of Surveying Cell Phone Numbers in the United States: 2007 and Beyond

By the late 1970s, household telephone coverage grew to exceed90 percent in the United States, and by the mid-1980s telephonesurveying of the general public had become commonplace. Nevertheless,20 years later, the ability of researchers to reach representativesamples of the U.S. public via landline (wired) telephone surveysand gather reliable data is being seriously challenged for manyreasons, especially those related to cell phones and the growthof the "cell phone only" population. However, at present thereexists no widely accepted set of Cell Phone Surveying "bestpractices" for U.S. survey researchers to follow. Despite whatsome appear to believe, surveying persons reached on cell phonenumbers in the United States currently is a very complex undertakingif one wants to do it "right," i.e. to do it legally, ethically,and in ways that optimally allocate one's finite resources togather the highest quality data, and to analyze and interpretthose data accurately. This final "wrap-up" article in the specialissue provides a review of the empirical articles in the issuewith a focus on their practical implications for the decisionsthat researchers need to make regarding sampling, coverage,nonresponse, measurement, and weighting in surveys that includeinterviews with persons reached on cell phones. The articlealso highlights the practical implications of a number of legal,ethical, and other issues that relate to surveys in the UnitedStates that include cell phone numbers. Surveying the U.S. cellphone population is possible, if at a higher cost than surveyingtheir landline counterparts, and if with less precision thancurrently can be done surveying the landline population. Thenext five years should see a considerable growth in the methodologicaland statistical know-how that the survey community uses to plan,implement, and interpret cell phone surveys. There is a greatdeal that still must be learned.     

Sampling Telephone Numbers and Adults, Interview Length, and Weighting in The California Health Interview Survey Cell Phone Pilot Study

This article describes several features included in a CaliforniaHealth Interview Survey cell phone pilot study that differ fromearlier cell phone surveys conducted in the United States. Onedifference is that the study used a screening design and onlyadults living in cell-only households were interviewed. Mostof the previous studies used dual frame designs. Another differencewas the development and implementation of a within-householdadult sampling procedure to cover adults when cell phones wereshared in the household. The study was also intended to determineif conducting a cell phone interview of the same scope and lengthas a regular telephone interview was feasible. Most previoussurveys were focused on cell phone topics and were shorter thanthe comparable landline surveys. We then explore some interestingproblems that arise in weighting a cell phone survey using ascreening design. We conclude with a discussion of planninga new cell phone survey in 2007 that incorporates findings fromthis study.     

Reaching the U.S. Cell Phone Generation: Comparison of Cell Phone Survey Results with an Ongoing Landline Telephone Survey

Noncoverage rates in U.S. landline-based telephone samples dueto cell phone only households (i.e., households with no landlinebut accessible by cell phone) and the corresponding potentialfor bias in estimates from surveys that sample only from landlineframes are growing issues. Building on some of the few publishedstudies that focus on this problem, a study was conducted inthree states (Georgia, New Mexico, and Pennsylvania) as partof the Behavioral Risk Factor Surveillance System (BRFSS), theworld's largest ongoing public health telephone survey, to evaluatethe effectiveness of conducting the BRFSS interview with a sampledrawn from dedicated cell phone telephone exchanges and mixed-use(landline and cell phone) exchanges. Approximately 600 interviewswere conducted in each of two groups: cell phone only adults(n = 572) and adults with both a landline and a cell phone (n= 592). Making comparisons with data from the ongoing, landline-basedBRFSS survey, we report on response rates, demographic characteristicsof respondents, key survey estimates of health conditions andrisk behaviors, and survey costs. The methods used in this studyhave wide application for other U.S. telephone surveys.     

Improving Gambling Survey Research Using Dual-Frame Sampling of Landline and Mobile Phone Numbers

Gambling prevalence studies are typically conducted within a single (landline) telephone sampling frame. This practice continues, despite emerging evidence that significant differences exist between landline and mobile (cell) phone only households. This study utilised a dual-frame (landline and mobile) telephone sampling methodology to cast light on the extent of differences across groups of respondents in respect to demographic, health, and gambling characteristics. A total of 2,014 participants from across Australian states and territories ranging in age from 18 to 96 years participated. Interviews were conducted using computer assisted telephone interviewing technology where 1,012 respondents from the landline sampling frame and 1,002 from the mobile phone sampling frame completed a questionnaire about gambling and other health behaviours. Responses across the landline sampling frame, the mobile phone sampling frame, and the subset of the mobile phone sampling frame that possessed a mobile phone only (MPO) were contrasted. The findings revealed that although respondents in the landline sample (62.7 %) did not significantly differ from respondents in the mobile phone sample (59.2 %) in gambling participation in the previous 12 months, they were significantly more likely to have gambled in the previous 12 months than the MPO sample (56.4 %). There were no significant differences in internet gambling participation over the previous 12 months in the landline sample (4.7 %), mobile phone sample (4.7 %) and the MPO sample (5.0 %). However, endorsement of lifetime problem gambling on the NODS-CLiP was significantly higher within the mobile sample (10.7 %) and the MPO sample (14.8 %) than the landline sample (6.6 %). Our research supports previous findings that reliance on a traditional landline telephone sampling approach effectively excludes distinct subgroups of the population from being represented in research findings. Consequently, we suggest that research best practice necessitates the use of a dual-frame sampling methodology. Despite inherent logistical and cost issues, this approach needs to become the norm in gambling survey research.     

Telephone surveys under different frame constructions—evaluating differences in estimates,precision, and cost

Dual-frame, random-digit-dialing (DFRDD) surveys, using a frame of landline telephone numbers and a frame of cell phone numbers, have become the norm for telephone surveys. Two alternative frame constructions sample exclusively from a cell phone frame, referred to as the ‘single-frame cell,’ and sample from the listed landline frame and the cell phone frame, referred to as ‘listed/cell.’ The listed/cell frame construction differs from the DFRDD in that it does not select unlisted-landline frame members. We observe in our simulated data that the listed/cell frame construction results in estimates that more closely approximate the estimates from DFRDD compared with the single-frame cell, results in an improvement in precision compared with the DFRDD that is not as large as the improvement in the single-frame cell, and has lower cost than both the DFRDD and the single-frame cell. We conclude that a listed/cell frame construction might be a better solution than either a DFRDD or single-frame cell frame construction.     

Comparison of telephone RDD and online panel survey modes on CPGI scores and co-morbidities

The purpose of this study was to compare the influence of two survey modes – telephone random digit dialling (RDD) and stratified sampling of an online panel – on Canadian Problem Gambling Index (CPGI) scores and co-morbidities. An identical gambling survey was administered to 4000 South Koreans selected via random dialling of cell phone numbers and to 4330 South Korean members of an online panel. The online panelists were found to have significantly higher levels of tobacco use, drug or alcohol problems and mental health problems, higher employment status and lower happiness levels. However, even when controlling for these variables, CPGI scores for the online panel were significantly higher than those for the telephone interview. This appears to be due to higher levels of pathology among online panelists combined with potentially more valid self-reports due to enhanced anonymity.     

How Too Little Can Give You a Little Too Much: Determining the Number of Household Phone Lines in RDD Surveys

Accurately assessing the number of household phone lines inrandom-digit dialed (RDD) surveys for use in weighting has becomemore complicated over time. This study evaluates phone lineweighting by asking an in-depth battery of seven questions designedto measure the number of available land lines in the home moreprecisely. The results show that this weighting correction isnot so simple, and that inadequately parsing the type and useof household phone numbers produces an inaccurate weight. Failingexplicitly to remove irrelevant phone numbers, especially cellphones, produces a larger-than-appropriate weighting adjustment.Potentially more important on a practical level is that, whendone correctly, and even when "overdone," phone line weightinghad little impact across a diverse set of opinion and demographicvariables.     

A Review of Poll Everywhere Audience Response System

Poll Everywhere, an audience response system based on cell phone texting technology, was tested in two undergraduate social work classes with very positive results. A survey conducted in one class reveals that two-thirds of the students answered every question and 14% most of the questions; over 90% found text-based polling to be either easy or extremely easy to use; over 90% thought it helped them learn class material; and over 80% would recommend or highly recommend its use. The instructors, too, found many strengths to this system. It is very easy to use, proved to be an effective way to engage students and increase class participation, free for a class size up to 40 students, and free to students with cell phone plans with unlimited text messaging. With the vast majority of college students owning cell phones, and text messaging serving as their primary form of cell phone communication, this technology is an intuitive, cost-effective, user-friendly technology that can enhance students' learning and classroom experience, and instructors' effectiveness in teaching course material and assessing students' command of the same by examining the results of their polls.     

Reaching a representative sample of college students: A comparative analysis

ABSTRACT

Objective: To explore the feasibility of a random-digit dial (RDD) cellular phone survey in order to reach a national and representative sample of college students. Methods: Demographic distributions from the 2011 National Young Adult Health Survey (NYAHS) were benchmarked against enrollment numbers from the Integrated Postsecondary Education System (IPEDS). The sample quality was compared with the Harvard School of Public Health College Alcohol Study (1993), National College Health Risk Behavior Survey (1995), and National College Health Assessment (2011). Results: Overall, the NYAHS performed as well, if not better, than previous college health surveys at reaching important demographic subgroups. Conclusions: Cellular phone RDD is one feasible approach for studies of the general population of college students that can potentially generate national estimates of health behavior.     

Numbers vs. Rights: Trade‐Offs and Guest Worker Programs1

This paper examines the relationship between the number and rights of low‐skilled migrant workers in high‐income countries. It identifies a trade‐off: Countries with large numbers of low‐skilled migrant workers offer them relatively few rights, while smaller numbers of migrants are typically associated with more rights. We discuss the number‐vs.‐rights trade‐off in theory and practice as an example of competing goods, raising the question of whether numbers of migrants or rights of migrants should get higher priority. There is no easy or universal answer, but avoiding an explicit discussion of the issue – as has been done in recent guest worker debates – can obscure an important policy choice.     

The Impact of Cell Phone Noncoverage Bias on Polling in the 2004 Presidential Election

Despite concerns that the accuracy of preelection telephonepolls would be harmed by the omission of voters who could bereached only by cell phone, most national polls performed wellin predicting President George W. Bush’s reelection in2004, and state polls were generally accurate as well. The nationalexit poll conducted by the National Election Pool found that7 percent of Election Day voters had cell phone service butno land line; younger voters were far more likely to be cell-only:19 percent among those age 18–24 and 20 percent amongthose age 25–29. Within these two youngest age cohorts,cell-only voters were significantly more likely to be singleand childless. While cell-only voters were more supportive ofJohn Kerry than voters overall, they were similar to other voterswithin their own age cohort. Because of this, preelection telephonesurveys that weighted their data appropriately by age were notsignificantly biased by the absence of the cell-only voters.     

Mitofsky Waksberg: Learning From The Past

Warren Mitofsky and Joseph Waksberg were two of the most influentialresearchers in telephone surveys and survey research methods.Their development of the Mitofsky–Waksberg method forrandom digit dialing sampling revolutionized telephone samplingand surveys. Jointly and separately, Waksberg and Mitofsky wereinstrumental in the development of many innovative methods andapplications. This article reviews some of their contributionsand discusses how their approaches to these problems may bea model for addressing issues that are being encountered currentlyin the United States in cell phone research.     

Eliciting survey cooperation: incentives, self-interest, and norms of cooperation

Given the weaker ties to community as noted by scholars such as Robert Putnam, survey researchers should not be surprised by a decline in survey participation over the past 10 years. This research analyzes the use of incentives coupled with introductory themes emphasizing cooperation and helpfulness--cooperative norms in American society--to understand their effects on survey response. This article analyzes two separate experiments (one phone and one mail) that provide evidence that norms of cooperation matter in the decision to participate in a survey, suggesting that this is particularly true at the refusal conversion stage. These results indicate that survey researchers may use such themes to their advantage, especially when conducting a nonresponse follow-up in a mail survey.     

College students use cell phones while driving more frequently than found in government study

OBJECTIVE: Cell phone use while driving is hazardous; it quadruples the risk of a collision and multiplies the risk of a fatality nine-fold. The National Highway Traffic Safety Administration estimates that 8% of young drivers and 5% of all drivers use cell phones while driving. PARTICIPANTS AND METHODS: The authors trained graduate student volunteers to observe the daytime cell phone use of 3,650 drivers leaving the student exits of college parking structures at a large university. RESULTS: The student observers recorded a cell phone usage rate of 11.1%, which was significantly higher than that seen in the National Occupant Protection Use Survey (p<.00001). Female drivers were 1.51 times more likely to be using a cell phone while driving than were men (12.9% vs 8.6%, p<.001), and drivers with passengers were 0.15 times more likely to drive while telephoning than were solo drivers (1.8% vs 12.1%, p<.001). CONCLUSIONS: The authors offer suggestions for possible interventions to reduce this hazardous behavior.     

Random Digit Dialing: A Sampling Technique for Telephone Surveys

This paper describes an investigation into the efficiency ofa random-digit-dialed telephone survey for the collection ofhealth attitude information. Data come from a survey of adultsin Oakland County, Michigan, conducted during the 1976–77swine influenza immunization campaign. Information is presentedon the results of dialing to sample telephone numbers, the frequencyof nonworking numbers within the sample, problems with numbersthat were never answered, and precision of sample estimates.In addition, some rough estimates of cost are presented andcompared to survey costs reported in other studies. Findingssuggest that random digit dialing is an efficient survey method,both in terms of cost in implementation and sampling precision.     

Benford’s Law and Number Selection in Fixed-Odds Numbers Game

In fixed-odds numbers games, the prizes and the odds of winning are known at the time of placement of the wager. Both players and operators are subject to the vagaries of luck in such games. Most game operators limit their liability exposure by imposing a sales limit on the bets received for each bet type, at the risk of losing the rejected bets to the underground operators. This raises a question—how should the game operator set the appropriate sales limit? We argue that the choice of the sales limit is intimately related to the ways players select numbers to bet on in the games. There are ample empirical evidences suggesting that players do not choose all numbers with equal probability, but have a tendency to bet on (small) numbers that are closely related to events around them (e.g., birth dates, addresses, etc.). To the best of our knowledge, this is the first paper to quantify this phenomenon and examine its relation to the classical Benford’s law. We use this connection to develop a choice model, and propose a method to set the appropriate sales limit in these games.     

The blessings and burdens of communication: cell phones in Jamaican transnational social fields

Abstract Although much mention has been made of the importance of ICTs for transnational migrants, we know relatively little about how these technologies affect or change everyday transnational communications. Tracing the shift from community phone boxes to individually owned mobile (cell) phones in rural Jamaica, in this article I focus on the integration of mobile phones in Jamaican transnational communication. Equipped with a mobile phone, rural Jamaicans no longer rely on collect phone calls and expensive calling cards to initiate the connections between their friends and relatives living abroad. For many Jamaicans without access to a regular or reliable phone service prior to 2001, the mobile phone is viewed as an unadulterated blessing, transforming the role of transnational communication from an intermittent event to a part of daily life. For others, however, the mobile phone remains an object of ambivalence, bringing unforeseen burdens and obligations.     

Privacy and confidentiality considerations for collecting HIV risk network data among men who have sex with men and implications for constructing valid risk networks

Studies aiming to construct risk networks have historically collected network members' names, demographic characteristics and relational data (i.e., type, strength, duration, frequency of interaction, and HIV-related risk behaviors between the pair). Due to difficulties in constructing risk networks stemming from partner anonymity and the use of nicknames, some studies also collect network members’ screen names, phone numbers, physical attributes, and scars/tattoos to assist with entity resolution. In-depth interviews with 20 men who have sex with men and transgender women in Kentucky assessed privacy/confidentiality concerns as well as accuracy/recall issues associated with providing these details. Most preferred providing alters’ nicknames/first names only or a first name with the first letter of the last name. Many perceived screen names, phone numbers, and scars/tattoos to be too personal/identifying. Willingness to provide more detailed information varied by relationship type/strength, which could influence the validity of the resulting network.