effluent. If the cluster is nearby, then the effluent may be the cause of the disease. They can also study whether the disease cluster overlaps with the residences of workers in a specific type of occupation. It may turn out that the cluster is not due to nearby toxic effluent but rather that many residents in the disease cluster work in a mine that uses toxic chemicals.
Figure 1.25.Mapping clusters as hot spots. Hot spot analysis can uncover clusters of crime, different demographic groups, disease, natural hazard events, and much more. Map by author. Data source: Long Beach Police Department.
Figure 1.26.Spatial relationships. Geographers study the spatial relationship between features, such as how far apart they are (left) or whether they overlap (right). Image by author.
Statistical tools are often used to study spatial relationships. With spatial correlation, it is possible to analyze the strength and direction of spatial relationships (figure 1.27), be they positive, negative, or unrelated. A positive relationship is when both variables change in the same direction, as when places with high unemployment also have high rates of alcohol consumption. A negative relationship is when an increase in one variable leads to a decrease in another, as when areas with high unemployment have lower traffic fatalities due to people driving less. When there is no pattern of increase or decrease between two variables, they are unrelated, as when places with high unemployment have no correlation with the number of earthquakes.
Figure 1.27.Spatial correlation. Variables in the same place can be plotted to see if they have positive, negative, or no relationship. Image by author.
With quantitative analysis, the phrase “correlation does not imply causation” is commonly used to describe the case where variables can be correlated, but one variable does not cause the other to change. To build on an earlier example, a cancer cluster may be located near a toxic effluent site, leading some people to infer that cancer risk increases because of proximity to the site. But, in reality, there may be a third variable that is not being considered. Even though the cancer cluster correlates with distance to toxic effluent, it may turn out that the cancer is due to where residents of the cluster work. It may be that many residents of the cluster work in a mine that uses toxic chemicals and that exposure to those chemicals is causing the disease. Cancer may have a strong correlation with proximity to toxic effluent, but the proximity is not the cause.
It is therefore important to consider multiple explanations when looking at correlations and to use previous research and theory when determining which variables to include in an analysis. When mapping heart disease by county and determining which factors contribute to it, current scientific research says that variables such as smoking, diet, and physical inactivity are contributing factors. Rates of smoking, rates of high cholesterol from poor diet, and average hours of exercise per capita can be mapped on top of a heart disease map. With spatial statistical analysis, the strength of each variable can be analyzed in relation to rates of heart disease. It may become clear that some counties have high rates of heart disease primarily due to high rates of smoking, while others may have high rates due to a lack of physical activity.
Go to ArcGIS Online to complete exercise 1.4: “Spatial patterns and spatial relationships. An analysis of homicide patterns in Chicago.”
Places and regions
Many people are drawn to geography because they love to explore and learn about the great diversity of the world. From quaint towns along the coast of Italy to the busy markets of Casablanca, and from the scenic valley of Yosemite to the steppes of Kenya, the world offers a vast range of interesting landscapes to experience. To better study and understand the unique characteristics of the world’s landscapes—the locations and spatial patterns of human and physical features—geographers use the concepts of place and region.
Places
Places are locations with a set of physical and/or human features that make them unique from other locations. Because of their uniqueness, they typically have names that can be found on general reference maps. For example, Yellowstone National Park is a place that is distinguished by natural geysers; wolves and other wildlife; and a complex tourism infrastructure of lodging, restaurants, roads, and hiking trails. Manhattan is a place that is distinguished by dense, high-rise buildings; an economy focused on areas such as finance, law, and advertising; and landmarks such as Central Park and Times Square. Venice Beach in Los Angeles is a place with eccentric boardwalk venders and entertainers.
The unique combination of features within a place, when experienced by people, create what is known as a sense of place. Sense of place comes from an emotional reaction that forms as humans interact with places. Some places have a very strong sense of place, evoking either a positive or negative reaction in people. For many, a place such as Paris has a very strong, positive sense of place. History, architecture, street layout, cafés, pedestrian activity, and parks combine to create a unique sense of place that people are strongly attached to (figure 1.28). Because of this, demand for housing is strong and tourism is a flourishing industry there. In contrast, a neighborhood in a big city that is trash strewn, largely abandoned, and littered with remnants of drug use may have a strong negative sense of place that repels people.
Placelessness is the antithesis of sense of place. Some places lack uniqueness, offering homogenous landscapes that differ very little from other places. Many urban areas in North American cities consist of wide arterial streets lined by fast-food restaurants and gas stations. The architecture and design of these places remain basically the same, whether it is in Los Angeles, Miami, Atlanta, or Phoenix. Some argue that cookie-cutter suburban residential development is also placeless. By this argument, these developments consist of large swaths of homogenous suburban homes that lack design tied to local history or culture (figure 1.29).
Figure 1.28.Café in Paris. Paris is a city with a strong sense of place that comes from its unique combination of human and physical features. Photo by Stefano Ember. Stock photo ID: 237982663. Shutterstock.
When geographers talk about places, they typically focus on the wide range of characteristics that compose the place—the people, the built environment, the natural environment—and the ways in which these characteristics form either a strong sense of place or a bland placelessness.
People perceive and navigate through places, and develop a sense of place, through mental maps, which are the way humans organize places in their minds. Most people can draw a map of their city, country, or the world, but in all likelihood, there will be more detail and precision in areas that they move through on a regular basis or are exposed to through various media. You probably have a detailed mental map of your neighborhood, which includes the location of local businesses, parks, the location of homes of people you like to see (and those whom you do not), places that are pleasant to travel through, and places that are dangerous or unpleasant.
Mental maps influence how we move through our cities and neighborhoods, as people tend to follow familiar routes and avoid unfamiliar routes. People also move on the basis of perceived characteristics of areas in their mental maps, staying clear of areas seen as dangerous or staying in areas viewed as aesthetically pleasing.
Beyond our own neighborhoods and cities, we still form mental maps. Most Americans can draw a rough map of the United States as well as a partial map of the world with some countries and continents. Through the study of geography, our mental map becomes more detailed. Well-developed mental maps allow us to better understand our
