A simple nomogram for sample size for estimating sensitivity and specificity of medical tests
Sensitivity and specificity measure inherent validity of a diagnostic test against a gold standard. Researchers develop new diagnostic methods to reduce the cost, risk, invasiveness, and time. Adequate sample size is a must to precisely estimate the validity of a diagnostic test. In practice, resear...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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Wolters Kluwer Medknow Publications
2010-01-01
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| Series: | Indian Journal of Ophthalmology |
| Subjects: | |
| Online Access: | http://www.ijo.in/article.asp?issn=0301-4738;year=2010;volume=58;issue=6;spage=519;epage=522;aulast=Malhotra |
| _version_ | 1818548832832585728 |
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| author | Malhotra Rajeev Indrayan A |
| author_facet | Malhotra Rajeev Indrayan A |
| author_sort | Malhotra Rajeev |
| collection | DOAJ |
| description | Sensitivity and specificity measure inherent validity of a diagnostic test against a gold standard. Researchers develop new diagnostic methods to reduce the cost, risk, invasiveness, and time. Adequate sample size is a must to precisely estimate the validity of a diagnostic test. In practice, researchers generally decide about the sample size arbitrarily either at their convenience, or from the previous literature. We have devised a simple nomogram that yields statistically valid sample size for anticipated sensitivity or anticipated specificity. MS Excel version 2007 was used to derive the values required to plot the nomogram using varying absolute precision, known prevalence of disease, and 95% confidence level using the formula already available in the literature. The nomogram plot was obtained by suitably arranging the lines and distances to conform to this formula. This nomogram could be easily used to determine the sample size for estimating the sensitivity or specificity of a diagnostic test with required precision and 95% confidence level. Sample size at 90% and 99% confidence level, respectively, can also be obtained by just multiplying 0.70 and 1.75 with the number obtained for the 95% confidence level. A nomogram instantly provides the required number of subjects by just moving the ruler and can be repeatedly used without redoing the calculations. This can also be applied for reverse calculations. This nomogram is not applicable for testing of the hypothesis set-up and is applicable only when both diagnostic test and gold standard results have a dichotomous category. |
| first_indexed | 2024-12-12T08:25:31Z |
| format | Article |
| id | doaj.art-01894f0bd4a54cf1a905ab74f51f0cb3 |
| institution | Directory Open Access Journal |
| issn | 0301-4738 1998-3689 |
| language | English |
| last_indexed | 2024-12-12T08:25:31Z |
| publishDate | 2010-01-01 |
| publisher | Wolters Kluwer Medknow Publications |
| record_format | Article |
| series | Indian Journal of Ophthalmology |
| spelling | doaj.art-01894f0bd4a54cf1a905ab74f51f0cb32022-12-22T00:31:16ZengWolters Kluwer Medknow PublicationsIndian Journal of Ophthalmology0301-47381998-36892010-01-01586519522A simple nomogram for sample size for estimating sensitivity and specificity of medical testsMalhotra RajeevIndrayan ASensitivity and specificity measure inherent validity of a diagnostic test against a gold standard. Researchers develop new diagnostic methods to reduce the cost, risk, invasiveness, and time. Adequate sample size is a must to precisely estimate the validity of a diagnostic test. In practice, researchers generally decide about the sample size arbitrarily either at their convenience, or from the previous literature. We have devised a simple nomogram that yields statistically valid sample size for anticipated sensitivity or anticipated specificity. MS Excel version 2007 was used to derive the values required to plot the nomogram using varying absolute precision, known prevalence of disease, and 95% confidence level using the formula already available in the literature. The nomogram plot was obtained by suitably arranging the lines and distances to conform to this formula. This nomogram could be easily used to determine the sample size for estimating the sensitivity or specificity of a diagnostic test with required precision and 95% confidence level. Sample size at 90% and 99% confidence level, respectively, can also be obtained by just multiplying 0.70 and 1.75 with the number obtained for the 95% confidence level. A nomogram instantly provides the required number of subjects by just moving the ruler and can be repeatedly used without redoing the calculations. This can also be applied for reverse calculations. This nomogram is not applicable for testing of the hypothesis set-up and is applicable only when both diagnostic test and gold standard results have a dichotomous category.http://www.ijo.in/article.asp?issn=0301-4738;year=2010;volume=58;issue=6;spage=519;epage=522;aulast=MalhotraNomogramsample sizesensitivityspecificity |
| spellingShingle | Malhotra Rajeev Indrayan A A simple nomogram for sample size for estimating sensitivity and specificity of medical tests Indian Journal of Ophthalmology Nomogram sample size sensitivity specificity |
| title | A simple nomogram for sample size for estimating sensitivity and specificity of medical tests |
| title_full | A simple nomogram for sample size for estimating sensitivity and specificity of medical tests |
| title_fullStr | A simple nomogram for sample size for estimating sensitivity and specificity of medical tests |
| title_full_unstemmed | A simple nomogram for sample size for estimating sensitivity and specificity of medical tests |
| title_short | A simple nomogram for sample size for estimating sensitivity and specificity of medical tests |
| title_sort | simple nomogram for sample size for estimating sensitivity and specificity of medical tests |
| topic | Nomogram sample size sensitivity specificity |
| url | http://www.ijo.in/article.asp?issn=0301-4738;year=2010;volume=58;issue=6;spage=519;epage=522;aulast=Malhotra |
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