Sigma Study

The Sigma Study is a decennial survey of 99 small towns in Iowa that has been done in 1994, 2004, and 2014. To study the condition of Iowa small towns, residents of the 99 towns were surveyed to learn about their assessment of local services and amenities, social conditions, and perceptions of local quality of life. From these results we can generate a picture of the “typical” small town, which is called Sigma.

Research Design

Researchers at Iowa State University secured funding in 1994, 2004, and 2014 to study the condition of Iowa small towns. In each of those years, residents of 99 towns were surveyed to learn about their assessment of local services and amenities, social conditions, and perceptions of local quality of life. From the survey results, researchers created individual reports for each town and, by averaging the individual findings, generated a picture of the “typical” small town, which is called Sigma. You will find these reports for 1994, 2004, and 2014 at this website.

To ensure comparability, the same towns were studied in each wave. One town between 500 and 10,000 in population from each of Iowa’s 99 counties was selected at random in 1994 for the study. Towns that share a border with a metropolitan city were not included.

Even while the towns stayed the same, the residents selected to participate were different in each study. In 1994 and 2004, residents were randomly chosen from each town’s telephone directory. Today, telephone directories are less likely than in 1994 and 2004 to contain a complete list of households in a town. Therefore, in 2014 we contracted with Survey Sampling International to select a random sample of 150 households (and 15 replacement households) from lists of the mailing addresses associated with the towns’ zipcodes purchased from the U.S. Postal Service. Each selected household was sent a letter and a questionnaire by mail. The letter asked the adult head or one of the co-heads of the household to complete the survey. If the designated gender was not available (50% requested the male co-head, and 50% the female), the recipient was asked to complete the survey him or herself.

One week after the initial letter and questionnaire were mailed, participants received a postcard thanking them if they had already returned the questionnaire and reminding those who had not responded to do so. Three weeks later, another letter and questionnaire were sent to those who had not yet responded. At this time, residents were given the option of sending back the questionnaire through the mail or completing it online. In all 6,464 questionnaires were returned for a cooperation rate of 41.5 percent. This rate is considerably lower than the rates in the previous two waves. We replicated as closely as possible the design strategies that generated high response rates in 1994 and 2004. It is possible that these strategies are less effective in encouraging recipients to participate than they were in former times. The lower rate may also reflect survey fatigue experienced by Iowans deluged by election pollsters or perhaps a greater apathy toward community matters than existed in the past.

To our knowledge no other study examines these aspects of community life for such a large number of small towns over two decades. The information from this research provides truly unique insight into the changes that have occurred over the past two decades in Iowa's small towns and to a certain extent throughout the Midwest.