Basics of Research
Part 21: Categoric Analysis: Pearson Chi-Square Test
Investigators from St. Paul and Minneapolis, MN, sought to determine whether a didactic and manikin-based curriculum for training helicopter emergency medical service (HEMS) providers would result in differences in the successful placement of laryngeal mask airways (LMAs) versus intubating laryngeal mask airways (ILMAs) when subsequently tested on live patients in the operating room.1 The authors assessed differences in success rates statistically using the Pearson chi-square test (herein referred to as the chi-square test).Part 20: On Odds and Risk Ratios
A recent research article reported as its primary effect measure an adjusted odds ratio (OR) of 0.61 for the association between death from trauma and transport to hospital by helicopter emergency medical services (HEMS) versus ground emergency medical services (GEMS).1 Most people understand that an odds ratio > 1, or unity, denotes a positive association between the risk factor and outcome. When the odds ratio is < 1, most people understand that an inverse association is being reported. Assuming no significant residual systematic bias or random error, we conclude that, based on this analysis, HEMS transport was associated, on average, with less death after traumatic injury than transport by GEMS.Part 19: What is a P Value?
This review represents a nontechnical explanation of P values intended for the statistical novice.Experimental Studies in Air Medical Research
This article is the 18th in a multipart series designed to assist readers, particularly novices, in the area of clinical research. This article is focused on the process of developing a new research project. It provides tools to help those involved in beginning their own research projects.Non-Experimental Studies in Air Medical Research
This article is the 17th in a multipart series designed to assist readers, particularly novices, in the area of clinical research. This article is focused on the process of developing a new research project. It provides tools to help those involved in beginning their own research projects.Using Forms to Develop Research Projects
This article is the 16th in a multipart series designed to assist readers, particularly novices, in the area of clinical research. This article is focused on the process of developing a new research project. It provides tools to help those involved in beginning their own research projects.Inferential Statistics
This article is the 15th in a multipart series designed to improve the knowledge base of readers, particularly novices, in the area of clinical research. A better understanding of these principles should help in reading and understanding the application of published studies. It should also help those involved in beginning their own research projects.Hypothesis Testing
This article is the 14th in a multipart series designed to improve the knowledge base of readers, particularly novices, in the area of clinical research. A better understanding of these principles should help in reading and understanding the application of published studies. It should also help those involved in beginning their own research projects.Descriptive Data Analysis
This 13th article of the Basics of Research series is first in a short series on statistical analysis. These articles will discuss creating your statistical analysis plan, levels of measurement, descriptive statistics, probability theory, inferential statistics, and general considerations for interpretation of the results of a statistical analysis.Data Management
The most important part of any research project is the planning process. The more complete the planning, the smoother the project generally runs. This is particularly true for data collection and management. The plan for collecting, managing, and storing your data should be planned before the study begins. The investigator should have a specific plan in advance for how all data will be collected, formatted, and coded (if appropriate for some data elements) and the program(s) to be used to store and ultimately to analyze the data.Ethics, Human Rights, and Clinical Research
Ethical treatment of human subjects is fundamental to the conduct of research. Although respect for the rights of others has long been ingrained in health professionals, it was not until the mid 20th century that principles of conducting research with respect to human subjects and their rights were defined. Many principles and guidelines are in place today to protect subjects and assure that research is conducted in a way that prevents harm. Federal and international regulations ensure that research studies have institutional review board (IRB) review by an independent panel not involved with the research.Survey-based research: Performing the survey
This is the second article in this series on performing survey-based research. The first article provided an overview of the field of surveys and covered basic issues in survey design. Read that article first. It included a list of 10 commandments recommended for performing valid survey research and discussed many of them. This installment covers the remainder of that list, as well as issues of performing the survey itself, collecting the data, and considering some unique analytic approaches.Survey-based research: General principles
Surveys are a well-established and commonly employed category of research study design. A review of prior issues of Air Medical Journal and many other clinical journals usually reveals multiple articles that used a survey design format. Surveys, as a form of research, seem to be particularly popular among novice researchers. Unfortunately, many of those novice surveys are not well designed, and, as a result, surveys research has garnered a questionable reputation. Indeed, some journals (eg, American Journal of Emergency Medicine) will not even consider survey-based research for publication.Performing chart review studies
By definition, retrospective studies are those in which the events of interest have already occurred before the research project is begun. In other words, the interventions or exposures, the outcomes of interest, and all other relevant observations or data measurements have already occurred before the investigator begins the project. However, there are many different forms of retrospective studies, and it is unfair to lump them all together in one category. Different study designs can be used—for example, case-control studies versus retrospective cohort studies.Sources of bias in research design
The previous installment in the Basics of Research Series addressed sources of bias related to the measurement of research variables. In contrast, this issue addresses sources of bias within the research design, focusing specifically on internal and external validity. Note that although the word “validity” is common to both, validity here refers to validity of the entire study, rather than an individual variable.Measurement issues
This part of the Basics of Research series discusses issues of measurement. Good decisions relative to data elements and the method selected for their measure are essential in ensuring a quality study. Because of space considerations, this issue can only present basic content. For those desiring more in-depth knowledge, the classic book on psychometric theory by Nunnally and Bernstein may be of value.1Sampling methods: Selecting your subjects
After a basic research design has been selected for a proposed study, a number of details must be determined before the study is initiated. This involves developing the entire study protocol (i.e., fleshing out the protocol). This article in the Basics of Research series discusses decisions related to sampling and enrolling and randomizing study subjects. Because this area can be complex, definitions of some of the new terms used within the paper are given in Table 1.Research study designs: Non-experimental
The category of non-experimental designs is the most heterogeneous of the three classification categories (experimental, quasi-experimental, and non-experimental). Examples of the most common non-experimental designs are listed in Table 1. Although, in general, this category has the lowest level of scientific rigor, each design within this category varies as to its own individual level of scientific validity.Research study designs: Experimental and quasi-experimental
The first article in this series discussed developing an area of general interest and generating a proposed research question or hypothesis. The second article discussed reviewing the relevant body of literature on the subject and confirming that the research question is an appropriate one. The next step is planning the proposed research project. Translating a research idea into an actual project requires an understanding of research study designs. This article discusses the experimental research designs that are most appropriate for clinical investigations; the next article will address nonexperimental designs.Reviewing the literature
In the first part1 of the Basics of Research series, you learned how to get started in research and formulate an appropriate research question. The next step in developing a research project is to perform a comprehensive review of the relevant literature, defined by Burns and Grove as “an analysis and synthesis of research sources to generate a picture of what is known and not known about a particular situation or research problem.”2 The fundamental premise of the research question and subsequent selection of an appropriate study design depends on what gaps exist in current knowledge.Clinical research and critical care transport: How to get started
Though we often do not consciously acknowledge it, most of our clinical decisions have their basis in previous published research studies. Melnyk and Fineout-Overholt1 identify seven levels in a hierarchy of evidence to support clinical practice. All but one level relies on evidence generated from original research. Thus, research provides an important foundation for the provision of care during critical care transport. Clinical studies are potentially powerful tools for shaping the way in which care is delivered.
