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<table width="100%" summary="page for Tucker"><tr><td>Tucker</td><td align="right">R Documentation</td></tr></table>

<h2>
9 Cognitive variables discussed by Tucker and Lewis (1973)
</h2>

<h3>Description</h3>

<p>Tucker and Lewis (1973) introduced a reliability coefficient for ML factor analysis.  Their example data set was previously reported by Tucker (1958) and taken from Thurstone and Thurstone (1941).  The correlation matrix is a 9 x 9 for 710 subjects and has two correlated factors of ability: Word Fluency and Verbal.
</p>


<h3>Usage</h3>

<pre>data(Tucker)</pre>


<h3>Format</h3>


<p>A data frame with 9 observations on the following 9 variables.
</p>

<dl>
<dt><code>t42</code></dt><dd><p>Prefixes</p>
</dd>
<dt><code>t54</code></dt><dd><p>Suffixes</p>
</dd>
<dt><code>t45</code></dt><dd><p>Chicago Reading Test: Vocabulary</p>
</dd>
<dt><code>t46</code></dt><dd><p>Chicago Reading Test: Sentences</p>
</dd>
<dt><code>t23</code></dt><dd><p>First and last letters</p>
</dd>
<dt><code>t24</code></dt><dd><p>First letters</p>
</dd>
<dt><code>t27</code></dt><dd><p>Four letter words</p>
</dd>
<dt><code>t10</code></dt><dd><p>Completion</p>
</dd>
<dt><code>t51</code></dt><dd><p>Same or Opposite</p>
</dd>
</dl>



<h3>Details</h3>

<p>The correlation matrix from Tucker (1958) was used in Tucker and Lewis (1973) for the Tucker-Lewis Index of factoring reliability.
</p>


<h3>Source</h3>


<p>Tucker, Ledyard (1958) An inter-battery method of factor analysis, Psychometrika, 23, 111-136.
</p>


<h3>References</h3>


<p>L.~Tucker and C.~Lewis. (1973) A reliability coefficient for maximum likelihood factor analysis.
Psychometrika, 38(1):1&ndash;10.
</p>
<p>F.~J. Floyd and K.~F. Widaman. (1995)  Factor analysis in the development and refinement of clinical
assessment instruments., Psychological Assessment, 7(3):286 &ndash; 299.
</p>


<h3>Examples</h3>

<pre>
data(Tucker)
fa(Tucker,2,n.obs=710)
omega(Tucker,2)
</pre>


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