Ould be associated with inaccuracy in estimating proportions.Author Manuscript Author

Ould be associated with inaccuracy in estimating proportions.Author Manuscript Author Manuscript Author Manuscript Author ManuscriptMETHODSWe sought to recruit participants with a range of educational levels to expand generalizability beyond the Internet population and to ensure sufficient low-numeracy respondents to examine the numeracy hypothesis. One sample (n = 65) was recruited from waiting rooms at New Mangafodipir (trisodium) biological activity York-Presbyterian Hospital, a teaching hospital in a largely Hispanic neighborhood in northern Manhattan. These participants completed the questionnaire on a laptop computer. An additional 100 participants were recruited through the Virtual Laboratory of Columbia University’s Center for the Decision Sciences (https:// vlab2.gsb.columbia.edu/decisionsciences.columbia.edu/). The laboratory’s participant pool is diverse in age, education level, and geographic location, and all participants register with a PayPal account linked to a credit card, which helps prevent repeat participation. These participants completed the questionnaire on a secure Web site. Participants viewed a sequence of 6 unlabeled graphics, each showing a grid of yellow and blue stick figures, and were asked to estimate the percentage of blue figures by providing a number between 0 and 100 (Figure 1). Each graphic faded to gray after 10 s to ensure a uniform deadline and to discourage counting. The graphics were not BAY 11-7083 price described as depicting a risk or a chance. The instructions read, “In this section, we will show you pictures of groups of people, and ask you to guess what percentage of the people are blue. You will have 10 seconds to see each picture before it disappears. Don’t worry about being accurate. Don’t count the people. Just take a guess!” Each participant was shown 6 graphics: (A) 6 random; (B) 6 sequential; (C) 29 random; (D) 29 sequential; and then (E) the random version of either 40 , 50 , 60 , or 70 ; and (F) the sequential version of the same graphic as E (Table 1). Thus, all 165 respondents saw the 6 and 29 graphics, but one quarter saw the 40 , one quarter saw the 50 , one quarter saw the 60 , and one quarter saw the 70 graph. The order of presentation was A, F, C, B, D, and E. The graphics were developed in Adobe Flash CS Professional, version 9.0, using ActionScript 2.0 (Adobe Systems Inc., San Jose, CA) and embedded in an html/php questionnaire. The graphic showed 20 ?2 stick figures; the large array size was chosen to carry the implication of a large sample, as other researchers have found that small stickfigure groups can be interpreted as indicating small (and therefore less reliable) sample sizes.3 We also intentionally avoided 100 to discourage people from counting individual stick figures and to encourage a gestalt interpretation.Med Decis Making. Author manuscript; available in PMC 2017 June 02.Ancker et al.PageAfter completing this unlabeled graphics study, participants proceeded to a 2nd study of hypothetical health decisions in which the decision scenarios were illustrated with interactive graphics. Results of this 2nd study are reported elsewhere.18 Sociodemographic information was collected, and all participants took an 8-item numeracy scale modified from that of Lipkus and others.19 The scale assesses applied numerical skills such as the ability to convert between percentage and proportion (modification described by Ancker and others18). The study was approved by the Columbia University Institutional Review Board. All participants.Ould be associated with inaccuracy in estimating proportions.Author Manuscript Author Manuscript Author Manuscript Author ManuscriptMETHODSWe sought to recruit participants with a range of educational levels to expand generalizability beyond the Internet population and to ensure sufficient low-numeracy respondents to examine the numeracy hypothesis. One sample (n = 65) was recruited from waiting rooms at New York-Presbyterian Hospital, a teaching hospital in a largely Hispanic neighborhood in northern Manhattan. These participants completed the questionnaire on a laptop computer. An additional 100 participants were recruited through the Virtual Laboratory of Columbia University’s Center for the Decision Sciences (https:// vlab2.gsb.columbia.edu/decisionsciences.columbia.edu/). The laboratory’s participant pool is diverse in age, education level, and geographic location, and all participants register with a PayPal account linked to a credit card, which helps prevent repeat participation. These participants completed the questionnaire on a secure Web site. Participants viewed a sequence of 6 unlabeled graphics, each showing a grid of yellow and blue stick figures, and were asked to estimate the percentage of blue figures by providing a number between 0 and 100 (Figure 1). Each graphic faded to gray after 10 s to ensure a uniform deadline and to discourage counting. The graphics were not described as depicting a risk or a chance. The instructions read, “In this section, we will show you pictures of groups of people, and ask you to guess what percentage of the people are blue. You will have 10 seconds to see each picture before it disappears. Don’t worry about being accurate. Don’t count the people. Just take a guess!” Each participant was shown 6 graphics: (A) 6 random; (B) 6 sequential; (C) 29 random; (D) 29 sequential; and then (E) the random version of either 40 , 50 , 60 , or 70 ; and (F) the sequential version of the same graphic as E (Table 1). Thus, all 165 respondents saw the 6 and 29 graphics, but one quarter saw the 40 , one quarter saw the 50 , one quarter saw the 60 , and one quarter saw the 70 graph. The order of presentation was A, F, C, B, D, and E. The graphics were developed in Adobe Flash CS Professional, version 9.0, using ActionScript 2.0 (Adobe Systems Inc., San Jose, CA) and embedded in an html/php questionnaire. The graphic showed 20 ?2 stick figures; the large array size was chosen to carry the implication of a large sample, as other researchers have found that small stickfigure groups can be interpreted as indicating small (and therefore less reliable) sample sizes.3 We also intentionally avoided 100 to discourage people from counting individual stick figures and to encourage a gestalt interpretation.Med Decis Making. Author manuscript; available in PMC 2017 June 02.Ancker et al.PageAfter completing this unlabeled graphics study, participants proceeded to a 2nd study of hypothetical health decisions in which the decision scenarios were illustrated with interactive graphics. Results of this 2nd study are reported elsewhere.18 Sociodemographic information was collected, and all participants took an 8-item numeracy scale modified from that of Lipkus and others.19 The scale assesses applied numerical skills such as the ability to convert between percentage and proportion (modification described by Ancker and others18). The study was approved by the Columbia University Institutional Review Board. All participants.