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 Statistics for the Vascular Surgeon

Fundamental concepts

  • Sample versus population.
  • Random sampling.
  • Descriptive versus inferential.

Descriptive statistics

  • Data collection (nominal scale, ordinal scale, interval scale, ratio scale).
  • Frequency distribution, histogram, frequency polygon.
  • Location: measures of central tendency (arithmetic mean, median, mode), quartiles, deciles and percentiles.
  • Measures of variability and spread (minimum and maximum and range, variance, standard deviation).
  • Distribution curves (normal distribution, bimodal distribution), Kurtosis, outlier, skewness.

Inferential statistics

  • Standard error of mean, confidence intervals.
  • Significance tests, hypothesis testing, error of hypothesis testing, statistical power and sample size, p value, one-tail versus two-tail test).
  • Inference on means (student's t-test, comparison of means in paired and unpaired samples).
  • Inference on proportions (chi-square test, Fisher's exact test)

Regression and correlation

Nonparametric methods or distribution-free methods

  • Sighed rank test (Wilcoxon).
  • Wilcoxon rank sum test.
  • Mann-Whitney U test.
  • Kruskal-Wallis test.

Life-table analysis

  • Kaplan-Meier curve.
  • Log rank test or Mantel-Haenszel test.

Meta-analysis (goals, pitfalls).

Evaluation of a new diagnostic test

  • Reliability.
  • Sensitivity, specificity, positive predictive value, negative predictive value, overall accuracy.
  • Receiver operating characteristic curve.

References

MacNeill IB, Umphrey GJ. Biostatistics. Kluwer Academic Publishers, 1987.

Lewis AE. Biostatistics. New York : Van Nostrand Reinhold, 1984.

R.H. Riffenburgh. Statistics in medicine. San Diego : Academic Press, 1999.

Khachatryan A and Linardakis N. Biostatistics and epidemiology. New York : McGraw-Hill, 1998.

Indrayan A, Sarmukaddam SB. Medical biostatistics. New York : Marcel Dekker, 2001.

Posted June 2010