Normality tests for statistical analysis: a guide for non-statisticians

Asghar Ghasemi, Saleh Zahediasl, Asghar Ghasemi, Saleh Zahediasl

Abstract

Statistical errors are common in scientific literature and about 50% of the published articles have at least one error. The assumption of normality needs to be checked for many statistical procedures, namely parametric tests, because their validity depends on it. The aim of this commentary is to overview checking for normality in statistical analysis using SPSS.

Keywords: Normality; Statistical Analysis.

Figures

Figure. Histograms (Left) and P-P Plots (Right)…
Figure. Histograms (Left) and P-P Plots (Right) for Serum Magnesium and TSH Levels

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Source: PubMed

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