MATH 225 Week 1 Statistical Study Design Notes

MATH225 Data Collection and Experimental Design Designing a Statistical Study Identify the variable(s) of interest (the focus) and the population of the study. Develop a detailed plan for collecting data. If you use a sample, make sure the sample is representative of the population. Collect the data. Describe the data, using descriptive statistics techniques. Interpret the data and make decisions about the population using inferential statistics. Identify any possible errors. Example: A candy manufacturer is interested in the distribution of colors in each of its packages of candy sold. What should researchers do first? Write a question about the distribution of colors in each package. Choose a random sample of candy packages to analyze. Make some initial conclusions about the distribution of the colors. Make some initial conclusions about colors most people want. Data Collection: Types of Studies Observational Studies—You watch but you do not change existing conditions. Ex: Walmart/grocery store Experiment—a treatment is applied. Control Group: no treatment is applied…maybe a placebo is given. Ex: Fat free doritos and regular doritos Simulation: use of a mathematical or physical model to reproduce the conditions of a situation or process. Ex: Dangerous/expensive like new strain of disease and you want to see how fast it spreads Survey: investigation of one or more characteristics or a population. 2750820226©2024 Chamberlain University ©2024 Chamberlain University 1 Ex: Phone or paper surverys Example: Decide which method of data collection you would use to collect data for the study. A study of the effect on the taste of popular soda with less carbonation. Experiment Survey Simulation Observational Study A study of how fast a cloud of volcanic ash would spread over a metropolitan area. Experiment Survey Simulation Observational Study A study of how often people wash their hands in public restrooms. Experiment Survey Simulation Observational Study A study of the success of graduates of a large university in finding a job within one year of graduation. Experiment Survey Simulation Observational Study ©2024 Chamberlain University2 Example: A study is planned to research the effects of drinking coffee on hours of sleep. Would an experimental or observational study design be more appropriate? An observational study should be used because it is not possible to control whether or not a person drinks coffee. An observational study should be used because it is not possible to control the number of hours of sleep a person has. An experimental study should be used where the consumption of coffee is the experimental factor. An experimental study should be used where the number of hours of sleep is the experimental factor. Example: A scientist is interested in finding out the effect of soil quality on crop yield. Would an experimental or observational study design be more appropriate? An experimental study should be used with the crop yield as the controlled factor. An observational study should be used because the soil quality cannot be controlled. An experimental study should be used with the soil quality as the controlled factor. An observational study should be