OWL at Purdue University: Writing A Report: Theories and Models

owl home || writing lab and owl || handouts || workshops and presentations || internet resources

Getting Started With Your Report

Understanding the Sections of Your Report

Title page

Abstract

Table of contents

Introduction

Body

Theories,
Models,
and
Hypotheses

Materials
and
methods

Results:
presenting
data

Results:
interpreting data

Conclusions

Recommendations

References

Appendices

General Technical Writing Guidelines

Works Cited

Theories, Models, and Hypotheses

You may or may not need to include a section in which you discuss the theories and models upon which your research project is based. This section can be very important, especially for research articles, formal reports, or scientific papers, but sometimes it will not be required for lab reports and other homework assignments. If you do not have to include a section on theories and models, it will usually be because you are not positing an original hypothesis. This is likely to happen in a course for which you write lab reports. You may be required to conduct research to practice applying the theories and models you are learning about, but you will probably be given your hypothesis and won’t need to explain in your lab report where and how the hypothesis was developed since you did not actually develop it yourself. Regardless of whether you include a section on theories and models, your research will be informed by models and theories that other researchers have developed.

If you do need to include a section on theories, models, and your hypothesis, this section does not necessarily need to come before the materials and methods section of the report’s body. Placing this discussion early in the paper does help to frame the experiment and the data you will discuss later on, but some writers prefer to save this information until the results section of the report. Other writers prefer to include their discussion of theories and models in the introduction. If you decide to introduce theories and models in an early section of your paper, you can return to them later on in the report.

Theories attempt to explain how nature works; they are accepted if they work and because they help to explain most of the evidence that is available. Theories are not scientific laws; there is no absolute confirmation that they are true. Any project you undertake will certainly be founded upon a theory or set of theories. Models generally grow out of theories. They are “precise, mechanical construction[s] of how phenomena will behave” (Porush 100). Some models evolve even though there is no theory to explain them. In either case, models provide an important guide for future research and can help you set a program of study. However, it is important to understand that models are not necessarily the phenomena that you are interested in researching.

In most cases, you will need to include information about the theories and models that inform your research because these theories and models will directly affect the hypothesis that you propose and on which you base your research. When you develop hypotheses, you predict what you will find after you conduct your research. This prediction is based on existing theories, models, evidence, and logic.

How do I write about theories, models, and hypotheses?

It can seem overwhelming to explain and elaborate on theories and models while also developing your hypothesis. After all, in this section of the paper you will not discuss the data you found or how you found it; instead, you will introduce the theoretical basis for your project. Such a task can be intimidating, especially if you disagree with earlier theories or models and need to explain their weaknesses. It can help to consider your primary goals for this section. It's always best to talk with your professor, your adviser, or people in your workplace about what the best ways are to write reports in your field, or to consult other reports and use them as models or guides for your writing.

In your section, you may need to:

define and explain your hypothesis and the theories and models you used to develop it
define and explain competing hypotheses, theories, and models, including their strengths and weaknesses
compare and contrast the specific points where they agree or disagree

Prewriting on this section can also help you feel more comfortable including this information in your report and will help you to decide what needs to be included. The following questions are good ones to work through:

What do I expect this experiment to reveal? Why?
How does my hypothesis directly answer the question posed by the problem?
How does the hypothesis fit in with other hypotheses or more general theory? How will my work challenge or support the work of others?
What is the current theory to which it relates?
What are alternative views to this theory? What are the strengths and weakness of those views?
On what literature did I or can I base my explanation?

Notice how the authors of “Cortical Surface-Based Analysis” discuss both the strengths and weaknesses of the previous work that they build on in their research. This discussion of other research comes in their introduction, which is a common place for writers to put it.

Currently, the most widely used method of analyzing functional brain imaging data is to project the functional data from a sequence of slices onto a standardized anatomical 3-D space. The most common of these procedures is based on the Talairach atlas (Talairach et al., 1967; Talairach and Tournoux, 1988; see, e.g., Collins et al., 1994 for an automated prcedure). While this type of approach has certain advantages (ease of use, widespread acceptance, applicability to subcortical structures), it also has significant drawbacks.

These drawbacks derive from the fact that the intrinsic topology of the cerebral cortex is that of 2-D sheet with a highly folded and curved geometry. Estimates of the amount of ‘buried’ cortex range from 60 to 70% (Zilles et al., 1988; Van Essen and Drury, 1997), implying that distances measured in 3-D space between two points on the cortical surface will substantially underestimate the true distance along the cortical sheet, particularly in cases where the points lie on different banks of a sulcus.

The highly folded nature of the cortical surface also makes it difficult to view functional activity in a meaningful way. The typical means of visualization of this type of data is the project of functional activation onto a set of orthogonal slices. This procedure is problematic as regions of activity which are close together in the volume may be relatively far apart in terms of the distances measured along the cortical surface. In addition, the naturally two-dimensional organization of the cortical maps is largely obscured by the imposition of an external coordinate system in the form of orthogonal slices. These problems have led an increasing number of studies to make use of surface-based techniques for visualization (Tootell et al., 1995; DeYoe et al., Engel et al., 1997; Reppas et al., 1997; Talavage et al., 1997; Van Essen and Drury, 1997; Hadjikhani et al., 1998; Moore et al., 1998).

In order to facilitate the use of surface-based techniques for both display and analysis of structural and functional properties of the cerebral cortex, we have developed a unified procedure which begins with a previously reconstructed cortex (Dale and Sereno, 1993; Dale et al., 1998) and modifies it in order to achieve three separate but related goals.

This hypertext written by Angela Laflen
HTML and image maps by Erin Karper
August-September 2001

owl home || writing lab and owl || handouts || workshops and presentations || internet resources

This page is located at http://owl.english.purdue.edu/workshops/hypertext/reportw/bodytheories.html

Copyright ©1995-2004 by OWL at Purdue University and Purdue University. All rights reserved.
Use of this site constitutes acceptance of our terms and conditions of fair use.
To contact OWL, please refer to our contact information page so that you email the appropriate person. Requests for help sent to the wrong address may not receive a timely response.