anchor.diff:      <h2>References</h2>
   
       <ol>
  -      <li>Zarin, D. A., Tse, T. T., Williams, R. J., Califf, R. M., and Ide, N. C. (2011). <a href="http://www.nejm.org/doi/full/10.1056/NEJMsa1012065#t=article">The ClinicalTrials.gov results database – update and key issues</a>. N Engl J Med 364: 852–60.</li>
  -      <li><a href="http://www.fda.gov/RegulatoryInformation/Legislation/SignificantAmendmentstotheFDCAct/FoodandDrugAdministrationAmendmentsActof2007/default.htm">Food and Drug Administration Amendments Act of 2007</a>. Public Law 110-95.</li>
  -      <li>Laine, C., Horton R., DeAngelis C.D., et al. <a href="http://www.nejm.org/doi/full/10.1056/NEJMe078110#t=article">Clinical trial registration – looking back and moving ahead</a>. N Engl J Med 356: 2734–6.</li>
  -      <li><a href="http://ec.europa.eu/health/files/eudralex/vol-10/2008_07/c_16820080703en00030004_en.pdf">Communication from the Commission regarding the guideline on the data fields contained in the clinical trials database provided for in Article 11 of Directive 2001/20/EC to be included in the database on medicinal products provided for in Article 57 or Regulation (EC) No 726/2004</a>. In: European Commission, ed. Official Journal of the European Union, 2008. (2008/C 168/02.)</li>
  -      <li><a href="http://www.ema.europa.eu/ema/index.jsp?curl=pages/regulation/general/general_content_000044.jsp">Guidance on the information concerning paediatric clinical trials to be entered into the EU Database on Clinical Trials (EudraCT) and on the information to be made public by the European Medicines Agency (EMEA), in accordance with Article 41 of Regulation (EC) No 1901/2006</a>. In: European Commission, ed. Official Journal of the European Union, 2009. (2009/C 28/01.)</li>
  -      <li>Zarin, D. A., Ide, N. C., Tse, T. et al. (2007). <a href="http://www.ncbi.nlm.nih.gov/pubmed/17507347">Issues in the registration of clinical trials</a>. JAMA 297: 2112—2120.</li>
  -      <li>Moher, D., Liberati, A., Tetzlaff, J. and Altman, D. G. (for the PRISMA Group)(2009). <a href="http://annals.org/article.aspx?articleid=744664">Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement</a>, BMJ 339: 332—336.</li>
  -      <li>Tse, T., Williams, R. J., Zarin, D. A. (2009). <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2821287/">Reporting “basic results” in ClinicalTrials.gov</a>. CHEST 136: 295—303.</li>
  +      <li>Zarin, D. A., Tse, T. T., Williams, R. J., Califf, R. M., and Ide, N. C. (2011). <a target='_blank' href="http://www.nejm.org/doi/full/10.1056/NEJMsa1012065#t=article">The ClinicalTrials.gov results database – update and key issues</a>. N Engl J Med 364: 852–60.</li>
  +      <li><a target='_blank' href="http://www.fda.gov/RegulatoryInformation/Legislation/SignificantAmendmentstotheFDCAct/FoodandDrugAdministrationAmendmentsActof2007/default.htm">Food and Drug Administration Amendments Act of 2007</a>. Public Law 110-95.</li>
  +      <li>Laine, C., Horton R., DeAngelis C.D., et al. <a target='_blank' href="http://www.nejm.org/doi/full/10.1056/NEJMe078110#t=article">Clinical trial registration – looking back and moving ahead</a>. N Engl J Med 356: 2734–6.</li>
  +      <li><a target='_blank' href="http://ec.europa.eu/health/files/eudralex/vol-10/2008_07/c_16820080703en00030004_en.pdf">Communication from the Commission regarding the guideline on the data fields contained in the clinical trials database provided for in Article 11 of Directive 2001/20/EC to be included in the database on medicinal products provided for in Article 57 or Regulation (EC) No 726/2004</a>. In: European Commission, ed. Official Journal of the European Union, 2008. (2008/C 168/02.)</li>
  +      <li><a target='_blank' href="http://www.ema.europa.eu/ema/index.jsp?curl=pages/regulation/general/general_content_000044.jsp">Guidance on the information concerning paediatric clinical trials to be entered into the EU Database on Clinical Trials (EudraCT) and on the information to be made public by the European Medicines Agency (EMEA), in accordance with Article 41 of Regulation (EC) No 1901/2006</a>. In: European Commission, ed. Official Journal of the European Union, 2009. (2009/C 28/01.)</li>
  +      <li>Zarin, D. A., Ide, N. C., Tse, T. et al. (2007). <a target='_blank' href="http://www.ncbi.nlm.nih.gov/pubmed/17507347">Issues in the registration of clinical trials</a>. JAMA 297: 2112—2120.</li>
  +      <li>Moher, D., Liberati, A., Tetzlaff, J. and Altman, D. G. (for the PRISMA Group)(2009). <a target='_blank' href="http://annals.org/article.aspx?articleid=744664">Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement</a>, BMJ 339: 332—336.</li>
  +      <li>Tse, T., Williams, R. J., Zarin, D. A. (2009). <a target='_blank' href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2821287/">Reporting “basic results” in ClinicalTrials.gov</a>. CHEST 136: 295—303.</li>
       </ol>
   
     </div>
  
positive.code: 
      <h2>Use of appropriate statistical inference</h2>
  
      <p>If the AACT results data are to be used to support a meta-analysis or systematic review of the safety or efficacy of a particular intervention, then standard methods of meta-analysis or systematic review (e.g., the PRISMA statementxxxxxx[7]) should be used to appropriately account for study-to-study variability and other sources of uncertainty or bias. We recommend that authors consider the following points when deciding whether to report p-values, confidence intervals, or other probability-based inference when performing aggregate analysis of the ClinicalTrials.gov database:  </p>
  
      <h3>Is the data-generating mechanism random?</h3>
      <p>Methods of statistical inference such as p-values and 95% confidence intervals are most appropriate when used to quantify the uncertainty of estimates or comparisons due to a random process that generates the data. Examples of such processes include selection of a random sample of subjects from a broader population, randomly assigning a treatment to a cohort of subjects, or a coin toss about which we aim to predict future results.</p>
  
negative.code: 
      <p>The presence of a record in a dataset indicates that information was submitted to ClinicalTrials.gov for at least one variable in that data set before the data were downloaded from ClinicalTrials.gov. Some data elements are more/less likely than others to have missing information, depending on several known factors. For example:</p>
  
      <ul class='pointsToConsider'>
        <li><b>The data element being required by the FDAAA and/or the ClinicalTrials.gov website.</b> Refer to NLM's <a target='_blank' href='https://prsinfo.clinicaltrials.gov/definitions.html'>Study</a> and <a target='_blank' href='https://prsinfo.clinicaltrials.gov/results_definitions.html'>Results</a> data element definitions for specifics regarding these requirements. Requirements may have changed over the history of the ClincalTrials.gov database.</li>
        <li><b>The date when the data element was introduced.</b> Not all data elements were included in the database at the time of its launch in 2000, but were added later. Studies registered after FDAAA when into effect must meet more requirements than studies registered earlier in the life of ClinicalTrials.gov.</li>
        <li><b>The branching structure of questions.</b> The availability of certain questions to the person submitting data depends on answers to previous questions. For example, questions about bio-specimen retention are only available for observational studies. Therefore, interventional studies should be excluded when analyzing data elements pertaining to bio-specimens.</li>
        <li><b>The list of possible answers for data elements with a fixed set of responses.</b> For example, questions that include “N/A” as a possible response are likely to have fewer missing values than questions that do not provide a “N/A” response.</li>
  