<div dir="ltr">Dear ncl-talk,<div><br></div><div>I am computing a paired t test between control experiments sensitivity experiments to look at hurricane track, wind, and intensity errors. I compute the standard deviation of the differences and the avg of the differences, as well as a 95% confidence interval based on the differences.</div><div><br></div><div>Attached is my code, see lines starting on 1127. Is this the correct way to compute the standard deviation and average of the differences between experiments? My data is a function of (storm case, forecast cycle, forecast hour). Reason I ask is that when I do this procedure, the average differences I get using this method as a function of forecast hour (which is what I want) is this:</div><div><br></div><div><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">Variable: track_error_diff_avg (subsection)</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">Type: float</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">Total Size: 116 bytes</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures"> 29 values</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">Number of Dimensions: 1</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">Dimensions and sizes:<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>[29]</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">Coordinates: </span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">Number Of Attributes: 1</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures"> _FillValue :<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>9.96921e+36</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(0)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>3.574069</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(1)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>5.169381</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(2)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>4.654985</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(3)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>1.50052</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(4)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>3.559848</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(5)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>3.355001</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(6)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>4.764093</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(7)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>8.347384</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(8)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>7.4192</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(9)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>8.69336</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(10)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>12.72247</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(11)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>17.61452</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(12)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>17.19171</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(13)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>11.51769</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(14)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>9.379377</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(15)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>11.44438</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(16)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>7.419726</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(17)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>-3.023807</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(18)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>-18.86928</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(19)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>-3.98752</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(20)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>-4.023374</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(21)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>-14.1253</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(22)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>-7.246421</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(23)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>-10.78448</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(24)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>-23.74559</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(25)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>-40.31917</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(26)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>-51.49041</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(27)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>-34.30735</span></p>
<p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(28)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>-9.808663</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures"><br></span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">However, when I compute the raw difference from the average track fields, i.e. line 1154, I get these values:</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures"><br></span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">Variable: track_error_diff_avg (subsection)</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">Type: float</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">Total Size: 116 bytes</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures"> 29 values</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">Number of Dimensions: 1</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">Dimensions and sizes:<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>[29]</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">Coordinates: </span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">Number Of Attributes: 1</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures"> _FillValue :<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>9.96921e+36</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(0)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>3.574068</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(1)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>5.16938</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(2)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>4.654984</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(3)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>1.500519</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(4)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>3.559845</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(5)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>3.355003</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(6)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>4.764091</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(7)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>8.654808</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(8)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>8.30986</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(9)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>6.454712</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(10)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>10.45447</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(11)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>17.66672</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(12)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>20.24161</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(13)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>14.71471</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(14)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>13.84648</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(15)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>17.98428</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(16)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>9.601624</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(17)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>-0.5063171</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(18)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>-14.034</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(19)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>-3.797974</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(20)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>-0.2883911</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(21)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>-11.9198</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(22)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>-9.015442</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(23)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>-6.522919</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(24)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>-61.46265</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(25)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>-74.77875</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(26)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>-40.00131</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(27)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>52.12799</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">
</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">(28)<span class="gmail-Apple-tab-span" style="white-space:pre"> </span>76.7471</span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures"><br></span></p><p style="margin:0px;font-size:15px;line-height:normal;font-family:Menlo"><span style="font-variant-ligatures:no-common-ligatures">where the values start to deviate after index 8. Is there something I am doing wrong? I can't seem to find out why if so. Could it be there are missing values for certain storms and cycles? Any help is much appreciated. </span></p><div><br></div>-- <br><div class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div>Andrew Kren<br>
Research Scientist I, Global Observing Systems Analysis (GOSA) Group<br>
NOAA ESRL Global Systems Division (Rm 3C515)<br>
325 Broadway, Boulder, CO 80305<br>
<a href="tel:%28303%29%20497-5418" value="+13034975847" target="_blank">(303) 497-5418</a><span><font color="#888888"><br>
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