how to use ('select').each for different tables

how to use ('select').each for different tables

Hello:
I have two tables in a page and I can show different table based on the "EthnicityGroup". now I want to calculate risk based on different tables. Now when I click "calculate" button, it didn't return anything. Any help is appreciated.

HTML code:
......
<form name="form" autocomplete="off">
     <table id="tbEth">
        <tr>
            <td>Ethnicity Group:</td>
            <td style="padding:10px 0px">
            <label>
              <input type="radio" tabindex="1" name="EthnicityGroup" value="all" checked >
              All equations</label>
            <br>
            <label>
              <input type="radio" name="EthnicityGroup" value="asian" >
              Asian</label>
            <br>
            <label>
              <input type="radio" name="EthnicityGroup" value="white" >
              White</label>
          </td>
        </tr>
     </table>
     <table id="tbAsianSNP">     
        <tr>
         <th align="left">SNP  [Risk Allele]</th>
         <th align="left">Genotype</th>
        </tr>
        <tr>
         <td>rs111111  [A]</td>
         <td>
          <select name="ref1">
          <option value="" selected></option>
          <option value="2">AA</option>
          <option value="1">AG</option>
          <option value="0">GG</option>
          </select>
         </td>
        </tr>
        <tr>
         <td>rs222222 [T]</td>
         <td>
           <select name="ref2">
           <option value="" selected></option>
           <option value="2">TT</option>
           <option value="1">TC</option>
           <option value="0">CC</option>
           </select>
         </td>
        </tr>
        </table>
     
    <table id="tbWhiteSNP">
      <tr>
       <th align="left">SNP  [Risk Allele]</th>
       <th align="left">Genotype</th>
      </tr>
      <tr>
       <td>rs333333 [C]</td>
       <td>
        <select name="ref3">
          <option value="" selected></option>
        <option value="2">CC</option>
        <option value="1">TC</option>
        <option value="0">TT</option>
        </select>
       </td>
      </tr>
      <tr>
       <td>rs4444444 [T]</td>
       <td>
        <select name="ref4">
         <option value="" selected></option>
        <option value="2">TT</option>
        <option value="1">TC</option>
        <option value="0">CC</option>
        </select>
       </td>
      </tr>
         </table>
     
  
    <p id="pError" class="error">Please enter a value for all SNPs for the group listed above.</p>
    <p>
      <input id="btnCalc" type="button" class="btn" value="Calculate" >
      <input id="btnReset" type="button" value=" Reset " class="btn reset">
    </p>
</form>
<script src="calc_mn.js" type="text/javascript"></script>


Calc_mn.js code:
// JavaScript Document
$(document).ready(function(e) {
    $('#tbEth').change(changeForm);
    $('#btnCalc').click(displayRisk);
    });   
function getValuesFromForm() {
    var f = $('form').serializeArray();
    var val = new Object();
    $.each(f, function(i){
        val[f[i].name] = f[i].value;
    });
    return val;   
    }
         
function changeForm(){
....
}

function displayRisk() {
    var oc=getValuesFromForm();
    var bFieldsValid = true;
    $('select').each(function() {
// ----I only want to check if I select all for one table, either tbAsianSNP or tbWhiteSNP.
    if ($(this).prop('selectedIndex') == 0)
      return bFieldsValid = false;
  });
if(bFieldsValid == false) {
    .......
    if(this.id == 'btnCalc')
      $('#pError').show('fast');
  }
  else {
    var aRisk = calculateRisk(oc);
        var s = "<strong>" + aRisk.toFixed(2) + "</strong><br>";
    s += (aRisk < -1) ? "Low Risk" : ((aRisk > 1) ? "High Risk" : "Average Risk");
    $('#RiskScore').html(s);
    var s = Math.abs(aRisk.toFixed(2));
    s += ' standard deviations ';
    s += (aRisk >= 0) ? "higher " : "lower ";
    $('#spanExplanation1').html(s);
    $('#pInstructions').hide();
    $('#pError').hide('fast');
    $('#pExplanation').show();
    $('#RiskScore').show();
          );
  }
}

function calculateRisk(formValues) {
    var ob=formValues;
    var riskScore;
    switch (ob.EthnicityGroup){
        case 'asian':
        riskScore=0.69173*$("[name='ref1']").val()+
        1.23685*$("[name='ref2']").val();
break;
        case 'white':
        riskScore=0.34945*$("[name='ref3']").val()+
        0.67919*$("[name='ref4']").val();
break;
}
return riskScore;
}