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8: How to develop a hypothesis & research question

This chapter begins by defining and explaining the role of the hypothesis as part of the scientific method, and how a hypothesis differs from a theory. It continues to explain the characteristics of a good hypothesis, such as being specific, relatable, feasible, brief, and falsifiable. The chapter also explains what a null hypothesis is, and how to use the PICOT framework to convert a hypothesis into a research question. Dependent and independent variables are also outlined.

Glossary terms in this chapter

Hypothesis: A hypothesis is not a general question about the area, but a clear, falsifiable statement about what you think might be going on. Being falsifiable means that the idea can be reasonably tested and found either true or false.

Preponderance of evidence: The preponderance of evidence is an indication of whether the weight of evidence would leave one to conclude that a fact or theory is more likely than not.

Theory (scientific): A scientific theory is a principle that has been formed to explain a phenomenon or relationship based on substantiated evidence and data. A theory can often be formed to explain the results observed in a study.

Null hypothesis: The status quo, the business-as-usual case, whatever that is. It is the default position that your intervention did not have an effect. Formally, there is no significant difference between specified populations, any observed difference being due to sampling or experimental error.

Counterfactual: Counterfactual areas or groups can be used to represent what would have happened in the absence of an initiative, and better estimate the real impact on the areas or people receiving the intervention.

Dependent variable: The dependent variable is the variable being tested and measured. In evidence-based policing, it is the group, place, or population you want to impact.
Independent variable: The independent variable is something that you can adjust that you hope will influence your dependent variable.

Culture of curiosity: A policing culture that accepts some doubt and a willingness to question the current orthodoxy of policing.

Additional information and links

From a problem to a hypothesis

The dictionary people Merriam Webster have a very useful page that clearly delineates a hypothesis from a theory, and even goes into explaining when they get mixed up. as they note, "In non-scientific use, however, hypothesis and theory are often used interchangeably to mean simply an idea, speculation, or hunch"

In the same section, I introduce the phrase preponderance of evidence. As noted, the challenge with this is that it has a specific legal definition, as the legal burden of proof required in most civil (that is, non-criminal) trials. Generally, it requires that a case be shown to be 'more likely than not' or more than 50% likely, even if only slightly. This page discusses the legal standard in more depth, but bear in mind that I am applying it is a social science context, not a legal one in the book. 

The Philadelphia Foot Patrol Experiment

My personal website has an extensive page with a summary of the Philadelphia Foot Patrol Experiment and the various publications and reports that have come out of it. There is also a six minute video which provides a summary of the experiment for you. 

Related Reducing Crime podcast episode

PICOT framework

As this university webpage explains for nursing, but relevant to us, a good research query starts using an evidence-based practice framework developed from a well-constructed PICOT question. You can also find online many examples of the slightly shorter PICO framework. However, I prefer the addition of the time component because it aids setting a time boundary for when to evaluate an intervention. 

Related Reducing Crime podcast episode

Rachel Tuffin in the Director of Knowledge and Innovation at the College of Policing for England and Wales. We discuss the unique national role that the college has across law enforcement policy and training. This discussion is relevant to the chapter's theme of seeking challenging and interesting research questions in modern policing. 

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