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From |
Adam Olszewski <adam.olszewski@gmail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: replicating 2 X 2 data from a paper |

Date |
Tue, 2 Apr 2013 21:04:43 -0400 |

Hi Ariel, The footnote in the table says "Percent differences were calculated by dividing the absolute difference between groups by the usual care group value." So, the "Treatment difference" = (158-152)/152 = .03947368 How they got the P-value of 0.45 I have no idea. cci 152 158 95 96 gives 0.87 iri 152 158 95 96 gives 0.80 AO On Tue, Apr 2, 2013 at 8:16 PM, Ariel Linden, DrPH <ariel.linden@gmail.com> wrote: > Hi Fellow Statalisters, > > I am having a problem conceptualizing how to replicate data from a paper I > am reading (Bourbeau et al. 2003).* They have two groups (treatment = 96, > control= 95) who had 152 and 158 baseline hospitalizations, respectively. > > They describe in the text: " the comparison of the proportion of hospital > admissions or emergency department and medical visits was based on the chi2 > test. The Fisher exact test was used when the frequencies were small. > Percent difference effects of the intervention were calculated by dividing > the absolute difference between the intervention and usual care group > values." > > The table (table 2) shows the difference as 3.9% and a p-value of 0.45. > > So with this minimal information, I'd like to replicate the results, perhaps > using a 2 X 2 table format and test with chi2. > > My basic math (see below) does not seem to replicate the difference they > present. I get close using (treat-usual)/treat, but that is not consistent > with their text. Using a rate difference, I get something completely > different. In any case, I am not sure if there is a simple way to reproduce > these results consistent with how they claim to get there... > > usual treat (treat-usual)/treat > admits 152 158 0.038 > N 95 96 > admits/N 1.6 1.65 0.046 > > * Bourbeau JB, et al. Reduction of hospital utilization in patients with > chronic obstructive pulmonary disease. Arch Intern Med 2003: 163:585-591. > > Any help would be appreciated! > > Ariel > > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/faqs/resources/statalist-faq/ > * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/

**References**:**st: replicating 2 X 2 data from a paper***From:*"Ariel Linden, DrPH" <ariel.linden@gmail.com>

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