Normal curve equivalent

<h2 id="caution">Caution</h2>
<p>Careful consideration is required when computing <a href="/facts/Effect_sizes/mIpNrPte">effect sizes</a> using NCEs. NCEs differ from other scores, such as raw and scaled scores, in the magnitude of the effect sizes. Comparison of NCEs typically results in smaller effect sizes, and using the typical ranges for other effect sizes may result in interpretation errors.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a>
</p><p>Excel formula for conversion from Percentile to NCE:
</p>
=21.06*NORMSINV(PR/100)+50, where PR is the percentile value.
<p>Excel formula for conversion from NCE to Percentile:
</p>
=100*NORMSDIST((NCE-50)/21.06), where NCE is the Normal Curve Equivalent (NCE) value

<h2 id="external-links">External links</h2>
<ul><li><a href="http://www.psychometrica.de/normwertrechner_en.html">Norm Scale Calculator</a> (Utility for the Transformation and Visualization of Norm Scores)</li>
<li><a href="http://ststesting.com/explainit.html">Scholastic Testing Service</a>, a glossary of terms related to the <a href="/facts/Normal_distribution/UapjjPyQ">bell or normal curve</a>.</li>
<li><a href="http://www.ats.ucla.edu/stat/stata/faq/prank.htm">UCLA stats: How should I analyze percentile rank data</a> describing how to convert percentile ranks to NCEs with <a href="/facts/Stata/7Sx8QoJH">Stata</a>.</li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Mertler, C. A. (2002). Using standardized test data to guide instruction and intervention. College Park, MD: ERIC Clearinghouse on Assessment and Evaluation. (ERIC Document Reproduction Service No. ED470589) Normal curve equivalent (NCE): A normalized standardized score with a mean of 50 and a standard deviation of 21.06 resulting in a near equal interval scale from 0 to 99. The NCE was developed by RMC Research Corporation in 1976 to measure the effectiveness of the Title I Program across the United States and is often used to measure gains over time. (p. 3) <a href="http://www.eric.ed.gov/" target="_blank">http://www.eric.ed.gov/</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Rochester School Department webpage <a href="http://www.rochesterschools.com/Webmaster/StaffHelp/rdgstudy/nce.html" target="_blank">http://www.rochesterschools.com/Webmaster/StaffHelp/rdgstudy/nce.html</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>McLean, J. E., O'Neal, M. R., & Barnette, J. J. (2000, November). Are all effect sizes created equal? Paper presented at the Annual Meeting of the Mid-South Educational Research Association, Bowling Green, KY. (ERIC Document Reproduction Service No. ED448188) <a href="http://www.eric.ed.gov/" target="_blank">http://www.eric.ed.gov/</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
</ol>

Normal curve equivalent open-in-new

Normal curve equivalent