To do experiments, scientists rely on assumptions. An assumption is a statement we assume to be true. In our everyday lives, we all make assumptions. For example, you probably assume that you will have clean water to drink every day. Name at least one more assumption that you make every day.

Assumptions help scientists to identify hypotheses. Hypotheses are assumptions put to a scientific test. In other words, a hypothesis is an assumption stated in such a way that scientists may determine whether evidence exists to support their assumption.

In this research, the scientists wanted to learn whether wildfire prevention activities were related to the number of wildfires occurring in particular communities. One set of activities the scientists studied was wildfire prevention education programs. In this research, the scientists assumed, and then hypothesized, that wildfire prevention education programs were related to the number of wildfires occurring in a community.

The scientists also hypothesized that community characteristics were related to the number of wildfires. All these hypotheses were based on assumptions made by the scientists. In science, assumptions are based on previous evidence, usually in the form of earlier research.

A wildfire is a type of wildland fire. It is an unplanned ignition that started naturally or by careless human action, either accidentally or intentionally. An ignition occurs when a fire is started.

Three conditions must be present for a fire to burn. Fire experts call the presence of these three conditions the fire triangle. The fire triangle includes the presence of fuel, oxygen, and a heat source (figure 1). Fuel is any flammable or burnable material. In the case of wildfires, fuel includes trees, grasses, brush, and even houses.

More fuel causes a more intense fire, and dry fuels help the fire to spread (figure 2). Air provides the oxygen that a fire needs to burn. Heat sources help spark the wildfire and bring fuel to temperatures hot enough to ignite. Lightning, burning campfires, or cigarettes—and even the sun—can provide sufficient heat to spark a wildfire.

While wildfires can have undesirable effects, they are a natural process needed by most forests to remain healthy. Foresters sometimes set fires on purpose and manage them safely. These prescribed fires are used to keep ecosystems healthy and to reduce the amount of fuel available for a future wildfire.

Wildfire prevention education programs include those programs that teach people about wildfires and how to prevent them (figure 3). These programs are focused on wildfires caused by human actions. Humans may cause wildfires accidentally or on purpose. Accidentally caused wildfires include those caused by children at play, uncontrolled brush fires, unattended campfires, faulty power lines and electrical equipment, smoking materials, cars dragging chains or other metal, and railroads. Sparks from cars or trains can ignite the brush alongside a railroad track or road. Even parking on tall, dry grass may cause a wildfire to ignite. In contrast to accidentally caused wildfires, people may also cause wildfires on purpose (called arson).

Scientists have found that wildfire prevention education programs may reduce the number of accidentally caused wildfires. Although wildfire prevention education programs cost money, research has shown that wildfire prevention activities may cost less than it costs to suppress a wildland fire.

The scientists in this research study were interested in wildfire prevention education programs occurring on a special set of U.S. lands. These lands are Tribal lands across the United States (figure 4). The scientists were interested in learning whether wildfire prevention education programs conducted over a period of time were effective at reducing the number of accidentally caused wildfires on Tribal lands. The scientists also wanted to test for evidence as to whether the cost of suppressing wildfires was greater or less than the cost of wildfire prevention programs on Tribal lands.

The scientists made a number of assumptions to conduct their research. First, the scientists made assumptions about what might cause or prevent accidental wildfires. The scientists assumed that three broad possible things cause or prevent accidental wildfires. These things included environmental conditions, social conditions, and wildfire prevention education programs.

Under each of these assumptions, the scientists identified variables to describe each of the things that might cause or prevent accidental wildfires (table 1).

The scientists used weather information that had been collected by others. This information included air temperature, wind speed, and measures of drought and the likelihood of wildfire. A drought is a long period of dryness. Because natural areas may be severely impacted in a wildfire, the amount of available fuel was difficult to estimate. The scientists, therefore, used the amount of natural area burned previously as a measure of available fuels.

To identify a community’s opportunity to visit wildlands, the scientists measured the number of roads, trails, and campgrounds in and near the communities they studied (figure 5). The scientists assumed that easier access to wildlands would be related to more accidental wildfire occurrences.

The scientists collected information about income and unemployment rates in the communities. The scientists assumed that lower income and higher unemployment rates would result in more community dissatisfaction. This dissatisfaction might result in less care while in wildland environments and more accidentally caused wildfires. Communities with higher dissatisfaction were assumed to have a lower sense of well-being.

The scientists asked people working with the Tribes for information about wildfire prevention education programs (figure 6). Seventeen Tribes responded with information about programs started and conducted between 1996 and 2011. The scientists identified the months when wildfire prevention education programs were conducted. The scientists also collected information about how much each prevention program cost per year.

The scientists identified and counted the accidental causes of wildfires on the 17 Tribal lands (table 2).

The number of wildfire prevention education programs was most related to the number of wildfires caused by fire use and by children at play. Wildfire prevention programs were also related to the number of equipment-caused wildfires. Generally, as the number of education programs increased, the number of accidentally caused wildfires decreased.

The scientists found that the number of wildfires started from smoking cigarettes was not related to the prevention education programs. When the weather variables described dry and windy conditions, wildfires were more likely to occur.

According to the scientists’ calculations, wildfire prevention education programs were related to the number of accidentally caused wildfires on the 17 Tribal lands. Based on their research, the scientists were able to estimate how many wildfires were avoided on Tribal lands with wildfire prevention education programs (table 3).

The scientists compared the costs of wildfire prevention programs with the average cost of suppressing a wildfire. The scientists found that yearly prevention education program costs were less than the costs of suppressing wildfires.

This research indicates that wildfire prevention education programs may reduce the number of accidentally caused wildfires. The scientists believe, however, that more research is needed to better understand the effects of wildland fire prevention programs conducted over longer periods of time.