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Are you a p-value worshipper?

Huak CY - Eur J Dent (2009)

View Article: PubMed Central - PubMed

Affiliation: National University of Singapore, Singapore.

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The trend of the over-emphasis on having the results of a research work to be statistically significant (P<.05) is still going strong today due to the fact most researchers are statistically-phobiaed... In this write-up, I want to encourage a research paper reader to firstly critique on the research process... Table 1 shows the stages of a research study that need to be addressed in detail before a credible and clinically relevant result could be obtained... It is essential that stages 1 & 2 be properly set-up (available, hopefully, in the Materials & Methods of a paper) otherwise, even with the help of a statistician the results obtained will not be valid! For the results, the important question to ask is “Is the work clinically relevant to me?” An important point for a P-value worshipper to take note: “P-value is influenced by sample size, the larger the sample size, the likelihood of P<.05 is increased!”... For example, a researcher wants to determine the correlation between airway volume & lower face height; Table 2a shows a relatively poor correlation of r=0.271, P=0.100 with n=38... If we want to use lower face height to predict airway volume, the squaring of the correlation (r=0.217) shows that lower face height only explains about 5% of the variation in airway volume; whereas lower face height will explain 68% (squaring 0.827) of the variance in anterior face height... For the statistically-phobiaed, Table 4 gives a summary of the various statistical techniques (the detailed discussions are given in references –) that have a coverage of about 75–80% of all analyses performed in published articles; otherwise you may want to refer to the references – or alternatively seek a consult from a statistician... In conclusion, statistics is akin to a oven in a cake-baking process; an essential apparatus but the quality of the cake predominantly depends on the baker (the researcher) and the quality of the ingredients (data quality), though the brand of the oven does enhance a better cake-quality... It is strongly encouraged to get a statistician involved in the planning stage of your study to assist in the Stages 1 & 2 of the research process before finally setting up the database and statistical analysis... Are you still a p-value worshipper? I wish - no more, hurray!

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Scatter plot of a poor relationship.
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f1-0030161: Scatter plot of a poor relationship.

Mentions: For the results, the important question to ask is “Is the work clinically relevant to me?” An important point for a P-value worshipper to take note: “P-value is influenced by sample size, the larger the sample size, the likelihood of P<.05 is increased!”. For example, a researcher wants to determine the correlation between airway volume & lower face height; Table 2a shows a relatively poor correlation of r=0.271, P=0.100 with n=38. But when n was doubled, though the relationship remains poor, the P-value has become significant (P=0.018), see Table 2b – the impact of sample size! Figure 1 shows the graphical presentation of the poor relationship. A good clinical relationship (say between lower face height and anterior face height, r=0.827) will be given by r>0.7 (Figure 2).


Are you a p-value worshipper?

Huak CY - Eur J Dent (2009)

Scatter plot of a poor relationship.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2741185&req=5

f1-0030161: Scatter plot of a poor relationship.
Mentions: For the results, the important question to ask is “Is the work clinically relevant to me?” An important point for a P-value worshipper to take note: “P-value is influenced by sample size, the larger the sample size, the likelihood of P<.05 is increased!”. For example, a researcher wants to determine the correlation between airway volume & lower face height; Table 2a shows a relatively poor correlation of r=0.271, P=0.100 with n=38. But when n was doubled, though the relationship remains poor, the P-value has become significant (P=0.018), see Table 2b – the impact of sample size! Figure 1 shows the graphical presentation of the poor relationship. A good clinical relationship (say between lower face height and anterior face height, r=0.827) will be given by r>0.7 (Figure 2).

View Article: PubMed Central - PubMed

Affiliation: National University of Singapore, Singapore.

AUTOMATICALLY GENERATED EXCERPT
Please rate it.

The trend of the over-emphasis on having the results of a research work to be statistically significant (P<.05) is still going strong today due to the fact most researchers are statistically-phobiaed... In this write-up, I want to encourage a research paper reader to firstly critique on the research process... Table 1 shows the stages of a research study that need to be addressed in detail before a credible and clinically relevant result could be obtained... It is essential that stages 1 & 2 be properly set-up (available, hopefully, in the Materials & Methods of a paper) otherwise, even with the help of a statistician the results obtained will not be valid! For the results, the important question to ask is “Is the work clinically relevant to me?” An important point for a P-value worshipper to take note: “P-value is influenced by sample size, the larger the sample size, the likelihood of P<.05 is increased!”... For example, a researcher wants to determine the correlation between airway volume & lower face height; Table 2a shows a relatively poor correlation of r=0.271, P=0.100 with n=38... If we want to use lower face height to predict airway volume, the squaring of the correlation (r=0.217) shows that lower face height only explains about 5% of the variation in airway volume; whereas lower face height will explain 68% (squaring 0.827) of the variance in anterior face height... For the statistically-phobiaed, Table 4 gives a summary of the various statistical techniques (the detailed discussions are given in references –) that have a coverage of about 75–80% of all analyses performed in published articles; otherwise you may want to refer to the references – or alternatively seek a consult from a statistician... In conclusion, statistics is akin to a oven in a cake-baking process; an essential apparatus but the quality of the cake predominantly depends on the baker (the researcher) and the quality of the ingredients (data quality), though the brand of the oven does enhance a better cake-quality... It is strongly encouraged to get a statistician involved in the planning stage of your study to assist in the Stages 1 & 2 of the research process before finally setting up the database and statistical analysis... Are you still a p-value worshipper? I wish - no more, hurray!

No MeSH data available.