How to Design and Report Experiments is the perfect textbook and guide to the often bewildering world of experimental design and statistics. It provides a complete map of the entire process beginning with how to get ideas about research, how to refine your research question and the actual design of the experiment, leading on to statistical procedure and assistance with writing up of results.
While many books look at the fundamentals of doing successful experiments and include good coverage of statistical techniques, this book very importantly considers the process in chronological order with specific attention given to effective design in the context of likely methods needed and expected results. Without full assessment of these aspects, the experience and results may not end up being as positive as one might have hoped. Ample coverage is then also provided of statistical data analysis, a hazardous journey in itself, and the reporting of findings, with numerous examples and helpful tips of common downfalls throughout.
How To Design And Report Experiments Pdf
How to Design and Report Experiments is the perfect textbook and guide to the often bewildering world of experimental design and statistics. It provides a complete map of the entire process beginning with how to get ideas about research, how to refine your research question and the actual design of the experiment, leading on to statistical procedure and assistance with writing up of results.
While many books look at the fundamentals of doing successful experiments and include good coverage of statistical techniques, this book very importantly considers the process in chronological order with specific attention given to effective design in the context of likely methods needed and expected results. Without full assessment of these aspects, the experience and results may not end up being as positive as one might have hoped. Ample coverage is then also provided of statistical data analysis, a hazardous journey in itself, and the reporting of findings, with numerous examples and helpful tips of common downfalls throughout.
Table of contentsStep 1: Define your variables
Step 2: Write your hypothesis
Step 3: Design your experimental treatments
Step 4: Assign your subjects to treatment groups
Step 5: Measure your dependent variable
Frequently asked questions about experiments
In medical or social research, you might also use matched pairs within your between-subjects design to make sure that each treatment group contains the same variety of test subjects in the same proportions.
In a within-subjects design (also known as a repeated measures design), every individual receives each of the experimental treatments consecutively, and their responses to each treatment are measured.
Within-subjects or repeated measures can also refer to an experimental design where an effect emerges over time, and individual responses are measured over time in order to measure this effect as it emerges.
Experiments are always context-dependent, and a good experimental design will take into account all of the unique considerations of your study system to produce information that is both valid and relevant to your research question.
The key difference between observational studies and experimental designs is that a well-done observational study does not influence the responses of participants, while experiments do have some sort of treatment condition applied to at least some participants by random assignment.
Scientific reports should always be clear and explicit, so that their content can be judged properly and incorporated into our knowledge. A number of features are relevant, such as adequate ethical standards and statistical treatment. Crucially, the details provided must allow another researcher to be able to replicate the study, so that the study could be independently verified.
Moreover, while the guidelines mention anaesthesia and analgesia, it is important also to stress the separate importance of analgesia in recovery experiments, both for ethical considerations and because of the possibility of drug interactions that might confound the experiment. Further, tissue removed under terminal anaesthesia and studied post-mortem can be affected by not only the nature, but also the timing of killing. Details of the techniques used are also necessary to satisfy ethical considerations (Drummond, 2009). Thus, while ARRIVE is a convenient acronym for the guidelines, their reach and influence might be greater if we simply considered them to be guidelines for reporting research involving animals.
It is worth commenting on some of the issues that were identified in a survey of published biological science research, carried out by the NC3Rs, and that subsequently helped to inform the guidelines (Kilkenny et al., 2009). For example, the survey found that only 59% of 271 randomly chosen articles stated the hypothesis or objective of the study and the number and characteristics of the animals used (i.e. species/strain, sex and age/weight). Moreover most papers surveyed did not report using randomization (87%) or blinding (86%) to reduce bias in animal selection and outcome assessment. This comment reflects the basis of the guidelines on the principles for randomized controlled clinical trials.
It is important, however, to recognize that experimental strategies in pharmacological and other laboratory-based disciplines are normally completely different. In studies of large uncontrolled populations, variance can be primarily ascribed to genetic, behavioural and environmental diversity. On the other hand, animals used for research in pharmacology consist of small rigorously selected groups for species, strain, age and sex and controlled for diet, temperature and light exposure, etc., in order to minimize variance and, hence, the requirement for large numbers of experiments. In many laboratory experiments, blinding may not be possible.
I strongly recommend this book. The all-important steps of defining the research question and choosing an appropriate method are clearly written by these experienced authors and by doing so provide a framework, which if followed, would avoid many of the common difficulties encountered by those in training. The book is a succinct, clear, and readable treatise on this extremely important area. It should prove to be invaluable to researchers, practicing social scientists, students and anyone involved in the design and reporting of experiments Social Psychological Review
The introduction of a lab report states the objective of the experiment and provides the reader with background information. State the topic of your report clearly and concisely (in one or two sentences). Provide background theory, previous research, or formulas the reader should know. Usually, an instructor does not want you to repeat whatever the lab manual says, but to show your understanding of the problem.
Were any errors avoidable? Were they the result of equipment? If the flaws resulted from the experiment design, explain how the design might be improved. Consider, as well, the precision of the instruments that were used.
Evidence-based public health decisions are based on evaluations of intervention studies with randomized and nonrandomized designs. Transparent reporting is crucial for assessing the validity and efficacy of these intervention studies, and, it facilitates synthesis of the findings for evidence-based recommendations. Therefore, the mission of the Transparent Reporting of Evaluations with Nonrandomized Designs (TREND) group is to improve the reporting standards of nonrandomized evaluations of behavioral and public health interventions.
The TREND statement Cdc-pdf[338 KB]1 has a 22-item checklist Cdc-pdf[368 KB] specifically developed to guide standardized reporting of nonrandomized controlled trials. The TREND statement complements the widely adopted CONsolidated Standards Of Reporting Trials (CONSORT) statement developed for randomized controlled trials. A collective effort in promoting transparent reporting is valuable to improve research synthesis and advance evidence-based recommendations for best practices and policies. We encourage all researchers, funding agencies, journal editors, and reviewers to use the TREND Statement as a guide when designing evaluation studies, reporting evaluation results, and reviewing manuscripts for scientific publication.
The TREND statement was first published in a special issue of the American Journal of Public Health in March 2004. The issue was devoted to evaluation research. This special issue contains a number of papers related to the use of nonrandomized or quasi-experimental designs in the evaluation of interventions.
1 Des Jarlais DC, Lyles C, Crepaz N, and the TREND Group. Improving the reporting quality of nonrandomized evaluations of behavioral and public health interventions: The TREND statement. Am J Public Health. 2004;94:361-366.
In a typical experiment, the effect of different conditions on a biological system is compared. Experimental design is used to identify data-collection schemes that achieve sensitivity and specificity requirements despite biological and technical variability, while keeping time and resource costs low. In the next series of columns we will use statistical concepts introduced so far and discuss design, analysis and reporting in common experimental scenarios. 2ff7e9595c
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