In randomized controlled trials, prior to statistical analysis, the data are checked for outliers and erroneous data. Data-cleaning is defined as deleting-the-errors / maintaining-the-outliers. Statistical tests are, traditionally, not very good at distinguishing between errors and outliers. However, they should be able to point out main endpoint results that are closer to expectation than compatible with random sampling. E.g., a difference from control of 0.000 is hardly compatible with random sampling. As it comes to well-balanced random sampling of representative experimental data, nature will be helpful to provide researchers with results close to perfection.
However, because biological processes are full of variations, nature will never allow for 100 per cent perfection. Statistical distributions can account for this lack of perfection in experimental data sampling, and provide exact probability levels of finding results close to expectation.
This is a preview of subscription content, log in via an institution.
Buying options
Tax calculation will be finalised at checkout
Purchases are for personal use only
Learn about institutional subscriptionsPreview
Unable to display preview. Download preview PDF.
References
SAS. www.sas.com
SPSS. www.spss.com
S-plus. www.splus.com
Stata. www.stata.com
Levin RI, Rubin DS. p-value. In: Statistics for management. Eds Levin RI and Rubin DS, Prentice-Hall, New Jersey, 1998, pp 485–496.
Utts JM. p-value. In: Seeing through statistics. Ed Utts JM, Duxbury Press, Detroit, 1999, pp 375–386.
Cleophas TJ, Zwinderman AH, Cleophas AF. p-values. Review. Am J ther 2004; 11: 317–322.
Cleophas TJ, Zwinderman AH, Cleophas AF. p-values, beware of the extremes. Clin Chem Lab Med 2004; 42: 300–305.
Michelson S, Schofield T. p-values as conditional probabilities. In: The biostatistics cookbook. Eds Michelson S and Schofield T, Kluwer Academic Publishers, Boston, 1996, pp 46–58.
Petrie A, Sabin C. Explanation of p-values. In: Medical statistics at glance. Eds Petrie A and Sabin C, Blackwell Science Oxford UK, 2000, pp 42–45.
Matthews DE, Farewel VT. p-value. In: Using and understanding medical statistics. Eds Matthews DE and Farewell VT, Karger, New York, 1996, pp15– 18.
Riffenburgh RH. p-values. In: Statistics in Medicine. Ed Riffenburgh RH, Academic Press, San Diego, 1999, pp 95–96, 105–106.
Cleophas TJ, Cleophas GM. Sponsored research and continuing medical education. JAMA 2001; 286: 302–304.
Hansson L, Zanchetti A, Carruthers SG, Dahlof B, Elmfeldt D, Julius S, et al., for the HOT Study Group. Effects of intensive blood pressure lowering and low-dose aspirin in patients with hypertension: principal results of the Hypertension Optimal Treatment (HOT) randomised trial. Lancet 1998; 351:1755–1762.
Sandham JD, Hull RD, Brand RF, Knox L, Pineo GF, Doig CJ, et al., for the Canadian Critical Care Clinical Trials Group. A randomized, controlled trial of the use of pulmonary-artery catheters in high–risk surgical patients. N Engl J Med 2003; 348:5–14.
LIPID Study Group. Long-term effectiveness and safety of pravastatin in 9014 patients with coronary heart disease and average cholesterol concentrations: the LIPID trial follow-up. Lancet 2002; 359:1379–1387.
Heart Protection Study Collaborative Group. MRC/BHF Heart Protection Study of cholesterol lowering with simvastatin in 20536 high-risk individuals: a randomised placebo-controlled trial. Lancet 2002; 360:7–22.
Parisi AF, Folland ED, Hartigan P, on behalf of the Veterans Affairs ACME Investigators. A comparison of angioplasty with medical therapy in the treatment of single-vessel coronary artery disease. N Engl J Med 1992; 326:10–16.
Seppälä H, Nissinen A, Järvinen H, Huovinen S, Henrikson T, Herva E, et al. Resistance to erythromycin in group A streptococci. N Engl J Med 1992; 326:292–297.
Rafal ES, Griffiths CE, Ditre CM, Finkel LJ, Hamilton TA, Ellis CN, et al. Topical retinoin treatment for liver spots associated with photodamage. N Engl J Med 1992; 326: 368–374.
Barrett BJ, Parfrey PS, Vavasour HM, O'Dea F, Kent G, Stone E. A comparison of nonionic, low-osmolality radiocontrast agents with ionic, high-osmolality agents during cardiac catheterization. N Engl J Med 1992; 326:431–436.
Medical Research Council. Streptomycin treatment of pulmonary tuberculosis. Br Med J 1948; 2: 769–782.
Motulsky H. p-values, definition and common misinterpretations. In: Intuitive biostatistics. Ed Motulsky H, Oxford University Press, New York, 1995, pp96– 97.
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2009 Springer Science + Business Media B.V.
About this chapter
Cite this chapter
(2009). The Interpretation of The P-Values. In: Cleophas, T.J., Zwinderman, A.H., Cleophas, T.F., Cleophas, E.P. (eds) Statistics Applied to Clinical Trials. Springer, Dordrecht. https://doi.org/10.1007/978-1-4020-9523-8_10
Download citation
DOI: https://doi.org/10.1007/978-1-4020-9523-8_10
Publisher Name: Springer, Dordrecht
Print ISBN: 978-1-4020-9522-1
Online ISBN: 978-1-4020-9523-8
eBook Packages: Mathematics and StatisticsMathematics and Statistics (R0)