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<table width="100%" summary="page for stats.S"><tr><td>stats.S</td><td style="text-align: right;">R Documentation</td></tr></table>

<h2>Functions to plot Shewhart S chart</h2>

<h3>Description</h3>

<p>These functions are used to compute statistics required by the S chart.</p>


<h3>Usage</h3>

<pre>
stats.S(data, sizes)
sd.S(data, sizes, std.dev = c("UWAVE-SD", "MVLUE-SD", "RMSDF"))
limits.S(center, std.dev, sizes, conf)
</pre>


<h3>Arguments</h3>

<table summary="R argblock">
<tr valign="top"><td><code>data</code></td>
<td>
<p>the observed data values</p>
</td></tr>
<tr valign="top"><td><code>center</code></td>
<td>
<p>sample/group center statistic.</p>
</td></tr>
<tr valign="top"><td><code>sizes</code></td>
<td>
<p>samples sizes. Optional</p>
</td></tr>
<tr valign="top"><td><code>std.dev</code></td>
<td>
<p>within group standard deviation. Optional for <code>sd.S</code> function, required for <code>limits.S</code>. See <code>sd.xbar</code>.</p>
</td></tr>
<tr valign="top"><td><code>conf</code></td>
<td>
<p>a numeric value used to compute control limits, specifying the number of standard deviations (if <code>conf</code> &gt; 1) or the confidence level (if 0 &lt; <code>conf</code> &lt; 1).</p>
</td></tr>
</table>


<h3>Value</h3>

<p>The function <code>stats.S</code> returns a list with components <code>statistics</code> and <code>center</code>.
</p>
<p>The function <code>sd.S</code> returns <code>std.dev</code> the standard deviation of the statistic charted.
</p>
<p>The function <code>limits.S</code> returns a matrix with lower and upper control limits. 
</p>


<h3>Author(s)</h3>

<p>Luca Scrucca</p>


<h3>References</h3>

<p>Montgomery, D.C. (2005) <em>Introduction to Statistical Quality Control</em>, 5th ed. New York: John Wiley &amp; Sons. <br />
Wetherill, G.B. and Brown, D.W. (1991) <em>Statistical Process Control</em>. New York: Chapman &amp; Hall.
</p>


<h3>See Also</h3>

<p><code>qcc</code> </p>


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