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Table 3 Categories of statistical methods used to assess the statistical content of articles

From: Systematic review of analytical methods applied to longitudinal studies of malaria

Category

Brief description

Include

No statistical methods or descriptive statistics only

Describe basic features of data to provide simple measures of summaries

No statistical content, or descriptive statistics only e.g., percentages, means, standard deviations, standard errors, histograms

Contingency tables

Cross tabulations used to summarize the relationship between categorical data

Chi-square test, Fisher’s exact test, McNemar’s test

Epidemiologic statistics

Measures of association for outcome of interest such as disease and some exposure(s)

Relative risk, risk ratios, rate ratios, risk difference, rate difference, odds ratio, log odds, risk difference, attributable risk fraction, sensitivity, specificity

Multiway tables

Extend two-way relationships to include three or more variables

Mantel–Haenszel procedure, log-linear models, logistic regression

t-test

Assess mean differences between groups

One-sample, matched-pair, two-sample t-tests

Pearson’s correlation

Measures linear correlation between two variables

Classical product-moment correlation

Simple linear regression

Regression that summarizes relationships between two continuous variables, an explanatory and a response

Least-squares regression with one predictor and one response variable

Multiple regression

Extends the simple regression to include two or more explanatory variables for a response

Polynomial regression and stepwise regression

Analysis of variance

Assess within and between group differences in means

Analysis of variance, Analysis of covariance, simple linear contrasts, F-tests

Multiple comparisons

Methods for handling multiple inferences on same data sets

Bonferroni techniques, Scheffé’s contrasts, Duncan multiple-range methods, Newman–Keuls procedure

Non-parametric test

Tests used when data is not assumed to follow a particular distribution, and are based on ranks of data

Sign test, Wilcoxon signed-rank test, Mann–Whitney test, Kruskal–Wallis test, Friedman test, Kolmogorov–Smirnov test

Non-parametric correlation

Measure strength and direction of association between two variables

Spearman’s rho, Kendall’s tau, monotone regression, test for trend

Survival analysis

Methods where outcome variable is the time until the occurrence of an event

Actuarial life table, Kaplan–Meier estimator for survival, survival function, Cox model, other parametric survival models, rate adjustment, log-rank test, Breslow’s test

Sensitivity analysis

Examines sensitivity of outcome to small changes in parameters of model or in other assumptions

Sample size, multiple outcomes, model distribution assumptions

Transformation

Use of data transformation often in regression

Natural logarithm, square, cubic

Cluster analysis

Involves dividing a multivariate dataset into “natural” clusters (groups) for in-depth assessment

Hierarchical, K-means, two-step clustering

Repeated-measures analysis

Approaches that account for correlation for within-participant observations and non-constant variance in response over time

Generalized estimating equations (GEE), mixed-effects models, repeated measures ANOVA

Other

Other methods not specified in above

Receiver-operating characteristic, principal component analysis, power analysis, propensity score