## 2 Methods  
The data presented in this study come from the \"Teens and Mobile Phones\" study by the Pew Internet and American Life and the University of Michigan. The present paper focuses on the survey and focus group data pertaining to teen internet use. First, we define how we distinguish between types of internet access. There are two broad ways of connecting to the internet. The most common is to connect via what might be called the \"open\" internet where the user has access through a provider such as Comcast, AOL or the like. This type of access might also come through the network at a person's job, their school (as is the case with many teens in this paper), or at a public site such as a library. This type of internet access is often, but not only, PC centric. That is, we use our PC's to link up to the internet. The specific link might be through a cable or through a local WiFi node. The alternative is using the mobile internet. In this case, access to the internet is mediated through the network of a mobile phone operator such as Sprint or AT&T. There is no local node in the form of a WiFi connection point, rather the individual connects via their local cell tower. Payment is also different in the two systems. In the case of the open internet, it is often an \"all you can eat\" subscription where in the case of the mobile internet there is more likely to be a limitation on the number of bytes that can be downloaded per month before there is an extra charge. Even so-called unlimited mobile internet plans, a growing trend, can be subject to restriction with an extreme amount use. All of this is confounded in that companies can be both mobile internet as well as traditional \"open\" internet providers. In addition, it is possible to hook an advanced mobile phone up to a WiFi node just as it is possible to hook a PC up to the mobile internet. In this paper, when we discuss use of the mobile internet it is almost exclusively the case that the individual has an advanced mobile phone that accesses the internet via the mobile network. Bit for bit, this mobile internet access is perhaps the most expensive type of internet access. Here, we outline the data collection and analysis procedures. The survey results are taken from a parent-teen survey, conducted by the Princeton Survey Research Associates International. The response rate was 13.7% for landline phones and 11.2% for cell phone contacts. This telephone survey included 800 teen participants and their parents. Conducted between June and September of 2009, the sample design utilized random digit landline and mobile phone dialing provided by Survey Sampling International, LLC (SSI) according to PSRAI specifications. The sample was then weighted so that results were representative of American teenagers in accordance with the Census Bureau's 2008 Annual Social and Economic Supplement (ASEC). The margin of error for the weighted data is \(\pm\)3.8%. Among the questions asked, those most relevant to the current investigation pertain to internet access in general and mobile phone feature use, including mobile internet capability and connectivity. Question wording and response distributions for questions most relevant to the present paper can be found in Appendix A. This paper also draws from focus group data. The University of Michigan and the Pew Research Center's Internet and American Life Project conducted nine focus groups with teen mobile phone users in four American cities between June and October of 2009. Participants were strategically recruited to ensure a balance of age, gender, race, and socio-economic status. Three groups were co-ed, and the other six were divided by sex (_i.e._, three all male, three all female). Sessions were also divided according to age group, with middle and high school teens grouped separately.