The study, carried out by Professor Douglas Gentile, used data from Harris Interactive through an opt-in online survey. The survey itself actually reads, "because the sample is based on those who agreed to participate in the Harris Interactive panel, no estimates of theoretical sampling error can be calculated."
Gentile responded to this discovery by admitting making a mistake. "I'd assumed they had gathered the population initially as part of a random probability sample, I missed that when I was writing this up. That is an error then on my part." Michael Gallagher, CEO of The ESA, wrote in his letter to Dr Kail: "The concern arises from the fact that the sample group for the study was not randomly chosen… It was a 'convenience' sample of individuals who agreed to participate in the survey."
"As you are likely aware, such a sample is not truly representative of a national population group. Thus the results cannot be projected onto the broader population of children in this country. And the sampling error of plus or minus 3 per cent that Dr Gentile cited in the study is also meaningless," he wrote. "Based on the public comments of both Dr Gentile and Harris Interactive, we are requesting that any references to the study in your publication and on your website, clarify the methodological flaws in Dr Gentile's study and inform your readers how those flaws affect the accuracy of the study."
Written by: James Delahunty @ 28 Apr 2009 21:23
