document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=125473>Question 125473</A>: <I><SPAN STYLE=\"word-break: break-all;\"> This is a question concerning least squares. I was asked to derive the math for fitting a straight line to a set of data points with unequal error bars. I don't know how to do this. Please help!<BR>\n" );
document.write( "  Thanks </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #91922 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=91922\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> This is a question concerning least squares. I was asked to derive the math for fitting a straight line to a set of data points with unequal error bars. I don't know how to do this. <BR>\n" );
document.write( "-------------------<BR>\n" );
document.write( "You could use Google to look at how a least squares formula works; use<BR>\n" );
document.write( "the search phrase \"least squares linear regression\".<BR>\n" );
document.write( "-------------<BR>\n" );
document.write( "Or, you might just think about it.<BR>\n" );
document.write( "Plot a small sense of points in the 1st Quadrant.<BR>\n" );
document.write( "Draw a line that \"kind of\" goes thru the middle <BR>\n" );
document.write( "of the group.<BR>\n" );
document.write( "Now, how would you move the line to get a \"better fit\"?<BR>\n" );
document.write( "When you move it you are changing the DIFFERENCE in the <BR>\n" );
document.write( "y coordinates between the line and a point that have <BR>\n" );
document.write( "the same x-value.<BR>\n" );
document.write( "some of those DIFFERENCES will be positive and some will<BR>\n" );
document.write( "be negative.  If you square them the numbers will all<BR>\n" );
document.write( "be positive; you can add them; then take the square root.<BR>\n" );
document.write( "Hopefully that will give you a number that is closer to<BR>\n" );
document.write( "being \"least squares number\".<BR>\n" );
document.write( "------------------<BR>\n" );
document.write( "Get the idea?<BR>\n" );
document.write( "===============<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );