ICR Whole Grain Study (Part B)

Experimental Study on Consumer Responses to Whole Grain Labeling Statements on Food Packages

OMB No. 0910-NEW

SUPPORTING STATEMENT

PART B

B. Statistical Methods

1. Respondent Universe and Sampling Methods

The respondent universe is members on Knowledge Networks’ KnowledgePanel.

KnowledgePanel^® is a probability-based online non-volunteer access panel. Panel members are recruited using a statistically valid sampling method with a published sample frame of residential addresses that covers approximately 97% of U.S. households. Sampled non-Internet households, when recruited, are provided a netbook computer and free Internet service so they may also participate as online panel members. KnowledgePanel consists of about 50,000 adult members (ages 18 and older) and includes persons living in cell phone only households. Due to voluntary withdrawal, involuntary retirement of high-tenured members, and the addition of new panelists from the on-going recruitment, actual panel size fluctuates across the year.

Until recently, KnowledgePanel’s probability-based recruitment had been based

exclusively on a national RDD frame. In 2009, KN initiated the use of an address based sample (ABS) frame to first supplement the RDD frame and subsequently replace it. ABS involves probability-based sampling of addresses from the U.S. Postal Service’s Delivery Sequence File. Randomly sampled addresses are invited to join KnowledgePanel through a series of mailings and by telephone follow-up to non-responders when a telephone number can be matched to the sampled address. Invited households can join the panel by one of several means: completing and mailing back an acceptance form in a postage-paid envelope; calling a toll-free hotline staffed by bilingual recruitment agents; or going to a dedicated KN recruitment Web site and completing the recruitment information online. The address sampling, conducted throughout the year, is done without replacement. Addresses with matched telephone numbers from the former RDD recruitment samples (for the last five years of calling) are also removed to eliminate duplication.

Once panel members are recruited and provide basic demographic information such as gender, age, race/ethnicity, they become “active” for selection for specific

surveys. Survey samples are drawn from among active members using a probability proportional to size (PPS) weighted sampling approach.

More details about KnowledgePanel’s design and general sampling approaches can be found at http://www.knowledgenetworks.com/knpanel/docs/KnowledgePanel(R)-Design-Summary-Description.pdf.

For this study, KN will aim to obtain 2,700 completes by adult members of its KnowledgePanel who will represent the panel in terms of gender, age (18-34, 35-54, and 55+), education (high school graduate or less education, and one year or more college education), and race/ethnicity (non-Hispanic white and other). The overall sample is drawn using a weighted proportional sampling approach so that all major population categories are proportionally represented in the sample and all members of the panel have a known probability for inclusion.  Quota sampling will also be used in order to increase the probability that the selected sample represents the characteristics of the population, in terms of gender, age, education, and race/ethnicity.

The key experimental hypotheses concern the effects of the whole-grain statements on consumers’ perceptions of the products. We estimate that 9 subjects per condition (N= 2,700 respondents) will provide adequate power to identify moderate detectable contrasts for all main effects (differences between the claims) with power around .8 for the primary between-subjects factors at the .05 significance level.

2. Procedures for the Collection of Information

Members on KnowledgePanel will be invited by email to complete the study online (see Appendix B for the invitation). The study is expected to take an average of 15 minutes to complete (see Appendix A for the questionnaire). Reminder emails will be sent to those who have not completed their questionnaires every three days during the field period (see Appendix C for the reminder).

The study includes the following topics: (1) nutrition and food label awareness & perceptions; (2) food label and whole grain claim responses; (3) general knowledge and attitudes about whole grain, food labels, and nutrition; (4) health status and demographic characteristics. Many label related questions are borrowed from the Health and Diet Survey that the agency commissioned in previous years (OMB No. 0910-0545) and FDA’s Experimental Studies of Nutrition Symbols on Food Packages (OMB No. 0910-0655).

3. Methods to Maximize Response Rates and Deal with Non-response

We will implement several procedures to maximize participation. We will conduct cognitive interviews and pretests to help improve understandability of the questionnaire, particularly to reduce participant burden, and to enhance interview administration. Since many label related questions in the study are borrowed from data collections previously commissioned by the agency or federal agencies, cognitive interviews will focus mostly on whole grain related questions. We will keep the study questionnaire at a reasonable length (15 minutes) to minimize breakoffs.

In addition, the contractor will send reminders and regularly monitor sampling output and returns to solve any problems daily throughout the course of the collection of information.

4. Test of Procedures or Methods to be Undertaken

The agency will conduct a round of pretest with 576 adults from the KnowledgePanel. The pretests will serve to address any unforeseen problems in administration of the interview.

5. Individuals Consulted on Statistical Aspects and Individuals Collecting and/or Analyzing Data

Knowledge Networks, as a sub-contractor to Research Triangle Institute, will collect the data. Dr. Jordon Peugh at KN was consulted on statistical aspects of the data collection. Yuanting Zhang, PhD, CFSAN, will lead the analysis of the data.

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