In doing research, we apply the scientific method to answer questions. For example, does cigarette smoking cause lung cancer? What are the mechanisms of weakness after stroke? Why do cells become cancerous? What properties are specific to the poison of South American tree frogs? We want to understand all the individuals being studied (i.e. people, cells, frogs, etc.) but it
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An important part of conducting sound science involves interpreting data correctly. Unfortunately, we don’t do that very well. For example, we are fooled by regression to the mean, we report findings when there are none, and we are overconfident about statistical power and significance. As scientists and lay persons, we want to be certain about research findings. But statistics only
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Many medical and scientific questions are the sort that cannot be answered using randomised study designs. For example, Does cigarette smoking cause lung cancer?, What is the risk hip fracture in adults?, and Do rats indirectly destroy coral reefs? Scientists often use observational cohort studies to answer these types of questions. In cohort studies, (1) a sample of subjects or
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In the first and second posts of this series, we performed simple linear regression of a continuous outcome on a single continuous predictor, but we also learned it is possible to include binary or categorical predictors in such regression models. How is this be done? The hsb2.csv dataset we have been using also contains the variable female where male participants
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In the previous post, we performed simple linear regression of science scores on reading scores from 200 students using ordinary least squares (OLS) estimation. This was done using Python’s Statsmodels package. What does the OLS output show and how should it be interpreted? Here is the figure of the individual subject data and the line of best fit, as well
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Hypothesis testing vs. Estimation Hypothesis tests require that populations are Normally distributed in order for the tests to be reliable. When samples are drawn from Normally distributed populations, the distributions of F or t statistics can be calculated for any given sample size, and the F or t statistic for a specific experiment can be obtained from the distribution. This
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Scientifically Sound 