Skip to main content

The Interpretation of the p-Values

  • Chapter
  • First Online:
Statistics Applied to Clinical Studies

Abstract

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. For example, 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.

This is a preview of subscription content, log in via an institution to check access.

Access this chapter

eBook
USD 16.99
Price excludes VAT (USA)
  • Available as EPUB and PDF
  • Read on any device
  • Instant download
  • Own it forever
Softcover Book
USD 129.99
Price excludes VAT (USA)
  • Compact, lightweight edition
  • Dispatched in 3 to 5 business days
  • Free shipping worldwide - see info
Hardcover Book
USD 109.99
Price excludes VAT (USA)
  • Durable hardcover edition
  • Dispatched in 3 to 5 business days
  • Free shipping worldwide - see info

Tax calculation will be finalised at checkout

Purchases are for personal use only

Institutional subscriptions

References

  • Barrett BJ, Parfrey PS, Vavasour HM, O’Dea F, Kent G, Stone E (1992) A comparison of nonionic, low-osmolality radiocontrast agents with ionic, high-osmolality agents during cardiac catheterization. N Engl J Med 326:431–436

    Article  PubMed  CAS  Google Scholar 

  • Cleophas TJ, Cleophas GM (2001) Sponsored research and continuing medical education. JAMA 286:302–304

    Article  PubMed  CAS  Google Scholar 

  • Cleophas TJ, Zwinderman AH, Cleophas AF (2004a) P-values. Review. Am J ther 11:317–322

    Article  PubMed  Google Scholar 

  • Cleophas TJ, Zwinderman AH, Cleophas AF (2004b) P-values, beware of the extremes. Clin Chem Lab Med 42:300–305

    Article  PubMed  CAS  Google Scholar 

  • Hansson L, Zanchetti A, Carruthers SG, Dahlof B, Elmfeldt D, Julius S, et al., for the HOT Study Group (1998) 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 351:1755–1762

    Google Scholar 

  • Heart Protection Study Collaborative Group (2002) MRC/BHF Heart Protection Study of cholesterol lowering with simvastatin in 20536 high-risk individuals: a randomised placebo-controlled trial. Lancet 360:7–22

    Article  Google Scholar 

  • Levin RI, Rubin DS (1998) P-value. In: Levin RI, Rubin DS (eds) Statistics for management. Prentice-Hall, Englewood Cliffs, pp 485–496

    Google Scholar 

  • LIPID Study Group (2002) Long-term effectiveness and safety of pravastatin in 9014 patients with coronary heart disease and average cholesterol concentrations: the LIPID trial follow-up. Lancet 359:1379–1387

    Article  Google Scholar 

  • Matthews DE, Farewel VT (1996) P-value. In: Matthews DE, Farewell VT (eds) Using and understanding medical statistics. Karger, New York, pp 15–18

    Google Scholar 

  • Medical Research Council (1948) Streptomycin treatment of pulmonary tuberculosis. Br Med J 2:769–782

    Article  Google Scholar 

  • Michelson S, Schofield T (1996) p-values as conditional probabilities. In: Michelson S, Schofield T (eds) The biostatistics cookbook. Kluwer Academic Publishers, Boston, pp 46–58

    Google Scholar 

  • Motulsky H (1995) P-values, definition and common misinterpretations. In: Motulsky H (ed) Intuitive biostatistics. Oxford University Press, New York, pp 96–97

    Google Scholar 

  • Parisi AF, Folland ED, Hartigan P, on behalf of the Veterans Affairs ACME Investigators (1992) A comparison of angioplasty with medical therapy in the treatment of single-vessel coronary artery disease. N Engl J Med 326:10–16

    Google Scholar 

  • Petrie A, Sabin C (2000) Explanation of p-values. In: Petrie A, Sabin C (eds) Medical statistics at glance. Blackwell Science, Oxford, pp 42–45

    Google Scholar 

  • Rafal ES, Griffiths CE, Ditre CM, Finkel LJ, Hamilton TA, Ellis CN et al (1992) Topical retinoin treatment for liver spots associated with photodamage. N Engl J Med 326:368–374

    Article  PubMed  CAS  Google Scholar 

  • Riffenburgh RH (1999) P-values. In: Riffenburgh RH (ed) Statistics in medicine. Academic, San Diego, pp 95–96, 105–106

    Google Scholar 

  • S-plus. www.splus.com. Accessed 14 Dec 2011

  • Sandham JD, Hull RD, Brand RF, Knox L, Pineo GF, Doig CJ, et al., for the Canadian Critical Care Clinical Trials Group (2003) A randomized, controlled trial of the use of pulmonary-artery catheters in high-risk surgical patients. N Engl J Med 348:5–14

    Google Scholar 

  • SAS. www.sas.com. Accessed 14 Dec 2011

  • Seppälä H, Nissinen A, Järvinen H, Huovinen S, Henrikson T, Herva E et al (1992) Resistance to erythromycin in group A streptococci. N Engl J Med 326:292–297

    Article  PubMed  Google Scholar 

  • SPSS. www.spss.com. Accessed 14 Dec 2011

  • Stata. www.stata.com. Accessed 14 Dec 2011

  • Utts JM (1999) P-value. In: Utts JM (ed) Seeing through statistics. Duxbury Press, Detroit, pp 375–386

    Google Scholar 

Download references

Author information

Authors and Affiliations

Authors

Rights and permissions

Reprints and permissions

Copyright information

© 2012 Springer Science+Business Media B.V.

About this chapter

Cite this chapter

Cleophas, T.J., Zwinderman, A.H. (2012). The Interpretation of the p-Values. In: Statistics Applied to Clinical Studies. Springer, Dordrecht. https://doi.org/10.1007/978-94-007-2863-9_10

Download citation

Publish with us

Policies and ethics