<div dir="ltr">When I try to get median age of all ZCTAs I get a warning message that I don&#39;t understand:<div><br></div><div><div>acs.data = acs.fetch(geography=geo.make(zip.code = &quot;*&quot;), </div><div>                     table.number = &quot;B01002&quot;, </div>
<div>                     col.names = &quot;pretty&quot;, </div><div>                     endyear = 2012, </div><div>                     span = 5)</div></div><div><br></div><div><div>Warning message:</div><div>NAs introduced by coercion </div>
</div><div><br></div><div>The resulting data.frame appears OK to me:</div><div><br></div><div><div>&gt; head(acs.data)</div><div>ACS DATA: </div><div> 2008 -- 2012 ;</div><div>  Estimates w/90% confidence intervals;</div>
<div>  for different intervals, see confint()</div><div>            Median Age by Sex: Median age -- Total: Median Age by Sex: Median age -- Male</div><div>ZCTA5 00601 36.4 +/- 0.5                            34.7 +/- 0.9                         </div>
<div>ZCTA5 00602 38 +/- 0.4                              37.2 +/- 0.5                         </div><div>ZCTA5 00603 38.4 +/- 0.6                            36.7 +/- 0.7                         </div><div>ZCTA5 00606 36.8 +/- 2                              36.8 +/- 3.2                         </div>
<div>ZCTA5 00610 38.6 +/- 0.6                            36.1 +/- 0.8                         </div><div>ZCTA5 00612 38.1 +/- 0.6                            36.9 +/- 1.2                         </div><div>            Median Age by Sex: Median age -- Female</div>
<div>ZCTA5 00601 37.7 +/- 1.5                           </div><div>ZCTA5 00602 38.7 +/- 0.6                           </div><div>ZCTA5 00603 40.1 +/- 0.6                           </div><div>ZCTA5 00606 36.8 +/- 2.9                           </div>
<div>ZCTA5 00610 40.5 +/- 0.5                           </div><div>ZCTA5 00612 39.2 +/- 1     </div></div><div><br></div><div>Can someone tell me what this warning means, and whether I need to be concerned about the resulting data?</div>
<div><br></div><div>Thanks.</div><div><br></div><div>Ari</div></div>