Statistical Assumptions
Statistical Assumptions - Related Videos
02:20
The Small x Assumption
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2020
If a reaction has a small equilibrium constant, the equilibrium position favors the reactants. In such reactions, a negligible change in concentration may occur if the initial concentrations of reactants are high and the Kc value is small. In such circumstances, the equilibrium concentration is approximately equal to its initial concentration. This estimation can be used to simplify the equilibrium calculations by assuming that some equilibrium concentrations are equal to the initial...
06:02
Visual Statistical Learning
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2023
Source: Laboratory of Jonathan Flombaum—Johns Hopkins University The visual environment contains massive amounts of information involving the relations between objects in space and time; certain objects are more likely to appear in the vicinity of other objects. Learning these regularities can support a wide array of visual processing, including object recognition. Unsurprisingly, then, humans appear to learn these regularities automatically, quickly, and without conscious awareness. The name...
01:29
Assumptions on Producer Behavior
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2024
Production Production involves the creation of products. For example, a consumer electronic company may manufacture mobile phones, pharmaceutical companies manufacture drugs, and a clothing manufacturer may produce t-shirts. Assumptions To simplify the analysis of a firm's production behavior, certain assumptions are made. These assumptions allow economists to create models that can predict and explain firm behavior. While they may not always reflect reality perfectly, they provide a useful...
01:15
Assumptions of Survival Analysis
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2025
Survival models analyze the time until one or more events occur, such as death in biological organisms or failure in mechanical systems. These models are widely used across fields like medicine, biology, engineering, and public health to study time-to-event phenomena. To ensure accurate results, survival analysis relies on key assumptions and careful study design. Survival Times Are Positively Skewed Survival times often exhibit positive skewness, unlike the normal distribution assumed in...
01:37
Statistical Significance
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2026
Once data is collected from both the experimental and the control groups, a statistical analysis is conducted to find out if there are meaningful differences between the two groups. A statistical analysis determines how likely any difference found is due to chance (and thus not meaningful). In psychology, group differences are considered meaningful, or significant, if the odds that these differences occurred by chance alone are 5 percent or less. Stated another way, if we repeated this...
FAQs
Independence primarily affects the accuracy of uncertainty estimates. When observations are related in ways the analysis does not represent, standard errors, tests, or intervals may no longer reflect the information actually present in the data. Researchers therefore consider independence during study design and sampling, before relying on model-based conclusions from experimental or observational research.
Normality can support particular sampling distributions, while constant variance helps a model represent error consistently across observations or predicted values. These assumptions serve different roles and should not be treated as interchangeable. Checking each one separately helps researchers identify whether a method’s estimates, tests, or predictions are being affected by an inappropriate description of the data.
Assumptions usually need to be reasonably, rather than perfectly, satisfied for an analysis to be useful. The consequences of a departure depend on which condition fails and how strongly it conflicts with the model. Diagnostic evidence can show whether the issue threatens interpretation, prompting a transformation, robust method, or alternative model instead of automatic acceptance or rejection.
Assessment combines study design with evidence from the observed data. Researchers first consider how sampling and data collection affect independence, then examine diagnostic plots and residual analysis for patterns related to model errors. Formal tests can provide additional evidence, but they are part of a broader evaluation that connects the data, model structure, and intended conclusion.
These options become relevant when diagnostic plots, residual analysis, formal tests, or study-design concerns indicate that an assumption is not reasonably met. A transformation can change how the data are represented, whereas a robust method or alternative model changes how the analysis handles departures. The choice should address the identified problem and preserve interpretable conclusions.
In both settings, assumptions connect observed data with the probability model used for estimation, testing, or prediction. Experimental design may provide important support for independence, while observational data require careful attention to how sampling and relationships among observations affect the analysis. Explicit evaluation strengthens interpretation, reproducibility, and confidence in conclusions across research contexts.