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<h1>22. Virtuoso Functions Guide - COVAR_SAMP</h1>
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<h2>COVAR_SAMP</h2>
<div class="refpurpose">Returns the sample covariance of a set of number pairs.</div>
<div class="funcsynopsis">
<span class="funcdef">numeric <span class="function">COVAR_SAMP</span>
</span>
(<span class="paramdef">in <span class="parameter">expr1</span> any</span>,
<span class="paramdef">in <span class="parameter">expr2</span> any</span>);
</div>
<div class="refsect1">
<div class="refsect1title">Description</div>
<p>COVAR_SAMP returns the sample covariance of a set of number pairs. Both expr1 and expr2 are numeric expressions. Virtuoso applies the function to the set of (expr1, expr2) pairs after eliminating
all pairs for which either expr1 or expr2 is null. Then Virtuoso makes the following computation:</p>
<div>
<pre class="programlisting">(SUM(expr1 * expr2) - SUM(expr2) * SUM(expr1) / n) / (n-1)</pre>
</div>
<p>where n is the number of (expr1, expr2) pairs where neither expr1 nor expr2 is null.</p>
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<div class="refsect1">
<div class="refsect1title">Parameters</div>
<div class="refsect2">
<span class="refsect2title">expr1 – </span>
Number expression.</div>
<div class="refsect2">
<span class="refsect2title">expr2 – </span>
Number expression.</div>
</div>
<div class="refsect1">
<div class="refsect1title">Return Types</div>
<p>The function returns a value of type NUMERIC. If the function is applied to an empty set, then it
returns null.</p>
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<div class="refsect1">
<div class="refsect1title">See Also</div>
<p>
<a href="fn_var.html">VAR()</a>
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<a href="fn_var_samp.html">VAR_SAMP()</a>
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<a href="fn_var_pop.html">VAR_POP()</a>
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<a href="fn_stddev.html">STDDEV()</a>
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<a href="fn_stddev_samp.html">STDDEV_SAMP()</a>
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<a href="fn_stddev_pop.html">STDDEV_POP()</a>
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<a href="fn_regr_syy.html">REGR_SYY()</a>
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<a href="fn_regr_sxx.html">REGR_SXX()</a>
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<a href="fn_regr_sxy.html">REGR_SXY()</a>
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<a href="fn_regr_avgx.html">REGR_AVGX()</a>
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<a href="fn_regr_avgy.html">REGR_AVGY()</a>
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<a href="fn_regr_r2.html">REGR_R2()</a>
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<a href="fn_regr_count.html">REGR_COUNT()</a>
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<a href="fn_regr_intercept.html">REGR_INTERCEPT()</a>
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<a href="fn_regr_slope.html">REGR_SLOPE()</a>
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<a href="fn_covar_samp.html">COVAR_SAMP()</a>
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<a href="fn_covar_pop.html">COVAR_POP()</a>
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<a href="fn_corr.html">CORR()</a>
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