function disableHistory()
	{
	document.history.length(0);
	}


function preValidAnswers()
	{ 
	if ((document.pretest.question15[0].checked == false) 
	 && (document.pretest.question15[1].checked == false)
	 && (document.pretest.question15[2].checked == false)
	 && (document.pretest.question15[3].checked == false))
		{
		alert("You must select answer for question 15.");
		return false;	
		}
	return true;
	}

function postValidAnswers ()
	{ 
	if ((document.posttest.question1[0].checked == false) 
	 && (document.posttest.question1[1].checked == false)
	 && (document.posttest.question1[2].checked == false))
		{
		alert("You must select answer for question 1.");
		return false;	
		}
	if ((document.posttest.question2[0].checked == false) 
	 && (document.posttest.question2[1].checked == false)
	 && (document.posttest.question2[2].checked == false)
	 && (document.posttest.question2[3].checked == false))
		{
		alert("You must select answer for question 2.");
		return false;	
		}
	if ((document.posttest.question3[0].checked == false) 
	 && (document.posttest.question3[1].checked == false)
	 && (document.posttest.question3[2].checked == false)
	 && (document.posttest.question3[3].checked == false))
		{
		alert("You must select answer for question 3.");
		return false;	
		}
	if ((document.posttest.question4[0].checked == false) 
	 && (document.posttest.question4[1].checked == false)
	 && (document.posttest.question4[2].checked == false)
	 && (document.posttest.question4[3].checked == false))
		{
		alert("You must select answer for question 4.");
		return false;	
		}
	if ((document.posttest.question5[0].checked == false) 
	 && (document.posttest.question5[1].checked == false))
		{
		alert("You must select answer for question 5.");
		return false;	
		}
	if ((document.posttest.question6[0].checked == false) 
	 && (document.posttest.question6[1].checked == false)
	 && (document.posttest.question6[2].checked == false)
	 && (document.posttest.question6[3].checked == false))
		{
		alert("You must select answer for question 6.");
		return false;	
		}
	if ((document.posttest.question7[0].checked == false) 
	 && (document.posttest.question7[1].checked == false)
	 && (document.posttest.question7[2].checked == false)
	 && (document.posttest.question7[3].checked == false))
		{
		alert("You must select answer for question 7.");
		return false;	
		}
	if ((document.posttest.question8[0].checked == false) 
	 && (document.posttest.question8[1].checked == false)
	 && (document.posttest.question8[2].checked == false)
	 && (document.posttest.question8[3].checked == false)
	 && (document.posttest.question8[4].checked == false))
		{
		alert("You must select answer for question 8.");
		return false;	
		}
	if ((document.posttest.question9[0].checked == false) 
	 && (document.posttest.question9[1].checked == false))
		{
		alert("You must select answer for question 9.");
		return false;	
		}
	if ((document.posttest.question10[0].checked == false) 
	 && (document.posttest.question10[1].checked == false)
	 && (document.posttest.question10[2].checked == false))
		{
		alert("You must select answer for question 10.");
		return false;	
		}
	if ((document.posttest.question11[0].checked == false) 
	 && (document.posttest.question11[1].checked == false)
	 && (document.posttest.question11[2].checked == false)
	 && (document.posttest.question11[3].checked == false))
		{
		alert("You must select answer for question 11.");
		return false;	
		}
	if ((document.posttest.question12[0].checked == false) 
	 && (document.posttest.question12[1].checked == false)
	 && (document.posttest.question12[2].checked == false)
	 && (document.posttest.question12[3].checked == false))
		{
		alert("You must select answer for question 12.");
		return false;	
		}
	if ((document.posttest.question13[0].checked == false) 
	 && (document.posttest.question13[1].checked == false))
		{
		alert("You must select answer for question 13.");
		return false;	
		}
	if ((document.posttest.question14[0].checked == false) 
	 && (document.posttest.question14[1].checked == false)
	 && (document.posttest.question14[2].checked == false)
	 && (document.posttest.question14[3].checked == false))
		{
		alert("You must select answer for question 14.");
		return false;	
		}
	if ((document.posttest.question15[0].checked == false) 
	 && (document.posttest.question15[1].checked == false)
	 && (document.posttest.question15[2].checked == false)
	 && (document.posttest.question15[3].checked == false))
		{
		alert("You must select answer for question 15.");
		return false;	
		}

	return true;
	}