Experimental Research Design Lecture Notes PDF

EXPERIMENTAL RESEARCH DESIGN CHEM 409 Research Methods Department of Chemical and Forensic Sciences 1 Reading Assignment 2 Question 1 Define the term ‘hypothesis in the context of scientific research (2 marks...

EXPERIMENTAL RESEARCH DESIGN CHEM 409 Research Methods Department of Chemical and Forensic Sciences 1 Reading Assignment 2 Question 1 Define the term ‘hypothesis in the context of scientific research (2 marks) Question 2 State THREE reasons why hypotheses are an important aspect of scientific research (3 marks) Question 3 List at least 3 criteria a hypothesis must meet to be considered as being scientifically rigorous (3 marks) Question 4 For this question, each student will use the research article that has been approved for use as the subject of their literature review assignment as a case study (Please include title of article in response) After thoroughly reading the assigned article, write the hypothesis of the study using the a) Direct statement form (1 mark) b) Null hypothesis and its alternative (2 marks) c) And either the ‘if/then’ format or the ‘when/then format’ (1 mark) Question 5 List ONE mistake scientists make when developing a hypothesis and give one way a scientist can overcome this mistake (2 marks) Question 6 Define each of the following with respect to experimental research design a) Independent variable b) Dependent variable c) Continuous variable d) Categorical variable e) Confounding variable (5 marks) Total (20 marks) THE RESEARCH PROJECT Department of Chemical and Forensic 5 Sciences Experimental Research Design Experimental Research Design and Hypothesis Testing After development of a testable hypothesis to address the research problem, the next step is to design a method for testing the hypothesis Experimental Research Design is a scientific framework that allows researchers to manipulate one or more variables while controlling the test environment When testing a hypothesis, it is helpful to have a certain level of control and manipulate variables to discover different outcomes. Researchers can use experiments to determine cause and effect or study variable associations. Experimental design is a research method that enables researchers to assess the effect of multiple factors on an outcome Researchers can determine the relationship between each of the variables by:  Manipulating one or more independent variables (i.e., stimuli or treatments)  Applying the changes to one or more dependent variables (i.e., test groups or outcomes) With the ability to analyze the relationship between variables and using measurable data, you can increase the accuracy of the result. What are the features of good experimental design? A good experimental design requires:  Significant planning to ensure control over the testing environment  Sound experimental treatments  Properly assigning subjects to treatment groups Without proper planning, unexpected external variables can alter an experiment's outcome. To meet your research goals, your experimental design should include these characteristics:  Provide unbiased estimates of inputs and associated uncertainties  Enable the researcher to detect differences caused by independent variables  Include a plan for analysis and reporting of the results  Provide easily interpretable results with specific conclusions  The two basic types of experimental designs used in scientific research are true experimental and quasi-experimental designs In true experimental design, the researcher relies on specific controls over the variables being studied. S/he has control over how the independent variable will be manipulated and the assignment of subjects to test/control groups However, these conditions are unethical or impossible to achieve in some situations. E.g. deciding on which subject will be given a placebo and which will be given the treatment drug When it's unethical or impractical to assign participants randomly, that’s when a quasi-experimental design comes in. In quasi experimental design, the researcher does not have control over the assignment of subjects to treatment groups. E.g. A researcher may wish to study pre-existing groups after they receive different drugs When can a researcher conduct experimental research?  Various settings and professions can use experimental research to gather information and observe behavior in controlled settings.  Basically, a researcher can conduct experimental research any time they want to test a theory with variable and dependent controls.  Experimental research is an option when the project includes an independent variable and a desire to understand the relationship between cause and effect. Importance of experimental research Experimental research enables researchers to conduct studies that provide specific, definitive answers to questions and hypotheses. Researchers can test Independent variables in controlled settings to:  Test the effectiveness of a new medication  Design better products  Answer questions about nature Developing a quality research plan means a researcher can accurately answer vital research questions with minimal error. As a result, definitive conclusions can influence the future of the independent variable. Steps for developing a research experiment Experimental research requires a clearly defined plan to outline the research parameters and expected goals. There are five key steps in designing a successful experiment: 1. Define the variables and their relationship Your experiment should begin with a question: What are you hoping to learn through your experiment? The relationship between variables in your study will determine your answer. Define the independent variable (the intended stimuli) and the dependent variable (the expected effect of the stimuli). After identifying these groups, consider how you might control them in your experiment. Could natural variations affect your research? If so, your experiment should include a pre-test and post-test. 2. Develop a specific, testable hypothesis With a firm understanding of the system you intend to study, you can write a specific, testable hypothesis. What is the expected outcome of your study? Develop a prediction about how the independent variable will affect the dependent variable. How will the stimuli in your experiment affect your test subjects? Your hypothesis should provide a prediction of the answer to your research question. 3. Design experimental treatments to manipulate your independent variable Depending on your experiment, your variable may be a fixed stimulus (like a medical treatment) or a variable stimulus (like a period during which an activity occurs). Determine which type of stimulus meets your experiment’s needs and how widely or finely to vary your stimuli. 4. Assign subjects to treatment groups When you have a clear idea of how to carry out your experiment, you can determine how to assemble test groups for an accurate study. When choosing your study groups, consider:  The size of your experiment  Whether you can select groups randomly  Your target audience for the outcome of the study  You should be able to create groups with an equal number of subjects and include subjects that match your target audience.  Remember, you should assign one group as a control and use one or more groups to study the effects of variables. 5. Plan how you will measure the dependent variable This step determines how you'll collect data to determine the study's outcome. You should seek reliable and valid measurements that minimize research bias or error. You can measure some data with scientific tools, while you’ll need to operationalize other forms to turn them into measurable observations. Advantages of experimental research Experimental research is an integral part of our world. It allows researchers to conduct experiments that answer specific questions. While researchers use many methods to conduct different experiments, experimental research offers these distinct benefits:  Researchers can determine cause and effect by manipulating variables.  It gives researchers a high level of control.  Researchers can test multiple variables within a single experiment.  All industries and fields of knowledge can use it.  Researchers can duplicate results to promote the validity of the study.  Replicating natural settings rapidly means immediate research.  Researchers can combine it with other research methods.  It provides specific conclusions about the validity of a product, theory, or idea. Limitations Unfortunately, no research type yields ideal conditions or perfect results. While experimental research might be the right choice for some studies, certain conditions could render experiments useless or even dangerous. Before conducting experimental research, consider these disadvantages and limitations:  Required professional qualification- Only competent professionals with an academic degree and specific training are qualified to conduct rigorous experimental research. This ensures results are unbiased and valid.  Limited scope- Experimental research may not capture the complexity of some phenomena, such as social interactions or cultural norms. These are difficult to control in a laboratory setting.  Resource-intensive- Experimental research can be expensive, time- consuming, and require significant resources, such as specialized equipment or trained personnel.  Limited generalizability-The controlled nature means the research findings may not fully apply to real-world situations or people outside the experimental setting.  Practical or ethical concerns- Some experiments may involve manipulating variables that could harm participants or violate ethical guidelines.  Researchers must ensure their experiments do not cause harm or discomfort to participants. Applications of experimental design in ‘real life’ Experiments across all industries and research realms provide scientists, developers, and other researchers with definitive answers. These experiments can solve problems, create inventions, and heal illnesses Product design testing is an excellent example of experimental research.  A company in the product development phase creates multiple prototypes for testing. With a randomized selection, researchers introduce each test group to a different prototype. When groups experience different product designs, the company can assess which option most appeals to potential customers. Experimental research design provides researchers with a controlled environment to conduct experiments that evaluate cause and effect. Using the five steps to develop a research plan ensures you anticipate and eliminate external variables while answering life’s crucial questions. Reading assignment Define each of the following terms with respect to experimental research design a) Independent variable b) Dependent variable c) Continuous variable d) Categorical variable e) Confounding variable  Second, you may need to choose how finely to vary your independent variable.  Sometimes this choice is made for you by your experimental system, but often you will need to decide, and this will affect how much you can infer from your results. Example In the soil warming experiment, you can treat temperature as: a) a categorical variable: either as binary (high/low) or as levels of a factor (very low, low, average, high and very high) b) a continuous variable (degrees Celsius) When designing an experiment, you need to decide how you will control any potential confounding variables Confounding variables - also called a confounder or confounding factor, is a third variable in a study exhibiting a potential cause-and-effect relationship. A confounding variable is related to both the supposed cause and the supposed effect of the study. It can be difficult to separate the true effect of the independent variable from the effect of the confounding variable.