Six National Studies
At the time of this writing, six national surveys have explored the scale and scope of household sector product innovation by product users. I begin with a very brief overview of the methods all these studies used. Full details will be found in the published reports on each. The six national surveys were carried out in the United Kingdom by von Hippel, de Jong, and Flowers (2012), in the United States and Japan by Ogawa and Pongtanalert (published in von Hippel, Ogawa, and de Jong 2011), in Finland by de Jong, von Hippel, Gault, Kuusisto, and Raasch (2015), in Canada by de Jong (2013), and in South Korea by Kim (2015). All six study samples included only new products and product modifications that had been developed by household sector individuals for personal or family use. To qualify for inclusion in our studies, we required that the developments provided useful functional improvements over products already available on the market, and that they had been developed within the three years prior to data collection. Aesthetic improvements were not included. Innovations that individuals developed at home for their jobs, rather than for personal or family use, were also not included in the study samples.
All six surveys utilized what are called nationally representative samples. A sample of this type is designed to mirror the demographic composition of a nation's population. For example, if a population contains a specific percentage of technically educated individuals, the sample will have a similar "representative” percentage of respondents with that characteristic. Because of this feature, we can project the findings derived from a nationally representative sample onto a nation's population at large. Data were collected by means of a questionnaire administered by telephone interviewers in the United Kingdom, Finland, and Canada and by means of Internet sites in the United States, Japan, and South Korea. Questions used in four of the six national studies were identical (UK, US, Japan, and South Korea). New questions were added to the fifth and sixth studies (Finland and Canada) to address additional issues. The full questionnaire used in the most recent study (Finland) is published in appendix 1 and also in de Jong (2016).