document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=523005>Question 523005</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Hi,\r<BR>\n" );
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document.write( "I am having problems with a chi-square related question.\r<BR>\n" );
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document.write( "Here is the question:\r<BR>\n" );
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document.write( "(a) Write the null and alternative hypothesis for a one-sided test to determine whether men are, on average, heavier than men from 20 years ago.\r<BR>\n" );
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document.write( "These are the hypotheses I have come up with:\r<BR>\n" );
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document.write( "Null Hypothesis – There is no difference between the average weight of men now and 20 years ago.<BR>\n" );
document.write( "Alternative Hypothesis – Men, on average, are heavier than men from 20 years ago.\r<BR>\n" );
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document.write( "(b) Carry out a test of the hypothesis in (a) at the 5% significance level, i.e. calculate the: <BR>\n" );
document.write( "-	Test statistic<BR>\n" );
document.write( "-	Critical value of the Normal Distribution for a one-sided test at the 5%        significance level\r<BR>\n" );
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document.write( "This is where I am having problems. I know how to do chi-square (I'm assuming we have to use chi-square as that's what we have been using in the other questions) when I have the data, ie. observed and expected. What I am unsure about is what data to use as this is all I have been provided with:\r<BR>\n" );
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document.write( "From data collected 20 years ago, the average weight of an adult male was 71 kilograms and the standard deviation 7.2 kilograms.\r<BR>\n" );
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document.write( "Table: Weights (in kilograms) of a new random sample of 29 adult males\r<BR>\n" );
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document.write( "59	79	61	81	62<BR>\n" );
document.write( "82	66	68	83	69<BR>\n" );
document.write( "84	70	73	77	84<BR>\n" );
document.write( "74	88	76	78	91<BR>\n" );
document.write( "78	74	86	59	66<BR>\n" );
document.write( "73	74	75	76	 \r<BR>\n" );
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document.write( "So far I have been using the averaging weight of the new sample of men which is 74.7 and the average weight from 20 years ago which is 71 and trying to use a one-way chi-square method. So basically my table looks like this:\r<BR>\n" );
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document.write( "           Today    20 Years Ago<BR>\n" );
document.write( "Weight     74.7         71\r<BR>\n" );
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document.write( "First of all is this the correct way of doing it? If so, my next dilemma is trying to figure out the expected frequency from the observed. I know how to calculate the expected from a contingency table of 2 or more rows, but when i try to apply the same formula to just one row, the expected ends up the same as the observed, which surely cant be right?\r<BR>\n" );
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document.write( "If I am going about it totally the wrong way, any advice would be appreciated. I am not a mathematician or even studying it ,so apologies for my lack of knowledge.\r<BR>\n" );
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document.write( "Hopefully someone can help me out.\r<BR>\n" );
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document.write( "Ryan </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #347150 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=347150\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> That is not a Chi-Sq problem.  It is a 2-sample Z or T test problem.<BR>\n" );
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document.write( "Also, a strict rule for hypothesist testing requires that<BR>\n" );
document.write( "equality ALWAYS appears in the Null Hypothesis.<BR>\n" );
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document.write( "I think if you use Google you will be able to find examples<BR>\n" );
document.write( "online of a 2-Sample test.<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
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