Who can’t answer your Internet survey? Who is unable to view your spiffy new website? Who won’t be reached by your email newsletter? In survey research, we call the answer to these questions coverage error or the proportion of individuals in your population of interest who are unable to be sampled/reached. Although it’s a statistical concept, coverage error is also vital to getting your message out to those you want to hear it.
Coverage errors can be very different for populations depending on the mode of the survey. The rule of thumb around the Corona offices is that (with the exception of the homeless) all households have a door you can knock on, fewer have a home telephone you can reach through a random digit dial sample, fewer have an address you can reach using a commercial mailing list, and even fewer use the Internet and have email addresses. This hierarchy is why Corona recommends only conducting online surveys with targeted populations who are likely to be wired, as the coverage error inherent in online surveys of the general population means you’re going to get very biased results.
Now, thanks to the Federal government, we have firm data on who is missing from the wired population, so we have an idea of just how bad the coverage error is. NTIA, the National Telecommunications and Information Administration, just released some very interesting data on household Internet use as a part of their report on the state of broadband in the USA.
So who uses the Internet? In this post we’ll look at this question geographically—which states have higher and lower rates of Internet usage. And in part two we’ll look at this question demographically, to see how income, race and ethnicity, education, and household type are related to Internet usage.
What parts of the country have higher and lower Internet usage?
The banks of the Mississippi are a relatively poor place to do a general population online survey. Six [Mississippi (60 percent of household usage), Arkansas (62 percent), Louisiana (63 percent), Tennessee (66 percent), Kentucky (67 percent), & Missouri (67 percent)] of the ten states with the lowest rates of household Internet use are bordered by the river. The other four states with the lowest levels of household Internet use are West Virginia (58 percent), Alabama (61 percent), Oklahoma (64 percent), and South Carolina (67 percent).
The west is the place to find high rates of Internet usage, as five of the states [Alaska (84 percent), Utah (82 percent), Washington (82 percent), Colorado (79 percent), and Wyoming (76 percent)] with the highest rates of Internet usage are western. The other five states are New Hampshire (81 percent), Minnesota (79 percent), Vermont (79 percent), Kansas (77 percent), and Maryland (76 percent). Even in Alaska, which has the highest rate of household Internet usage, about one out of every six households does not use the Internet.
Those who use the Internet at home are more likely to respond to surveys, since the Internet is more readily available to them. Again, we see lower rates of in-home Internet availability in the southern United States and along the Mississippi, with rates hovering between 40 and 60 percent. This means that in these areas, nealry half of all households do not have Internet access in their homes! The highest rates (between 70 and 80 percent) are again in the west and northeast.
Broadband connections allow for more easy use of such services as streaming video, VOIP, and other bandwidth-intensive pursuits (including embedding video clips in surveys).
In twenty-four states currently less than half of all households have in-home broadband access, with six having a rate of less than 40 percent. Those six states, all in the southern United States, are West Virginia (33 percent), Mississipi (33 percent), Alabama (37 percent), Arkansas (38 percent), Oklahoma (39 percent), and South Carolina (39 percent).
In only three states is the rate of in-home broadband usage higher than 60 percent: New Hampshire (65 percent), Alaska (63 percent), and Massachusetts (61 percent).
This brief analysis shows that if a survey of the general population is your goal, the Internet is not the best place to do that–your coverage error will be high in areas of the southern United States and you will not even be able to reach 18 percent of the households in the most connected states. In our next post, we will examine just how bad the coverage error is nationwide by different demographic variables.