document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1132663>Question 1132663</A>: <I><SPAN STYLE=\"word-break: break-all;\"> A surprising number of people are scared of clowns. You expect that people will have more nightmares the night that they see clowns at the circus. To test this, you send a group of people to a circus with clowns, and a group to a circus without clowns, and measure the number of people in each group who have nightmares that night. Your data is shown below:\r<BR>\n" );
document.write( "\n" );
document.write( "           Nightmares	Nice dreams<BR>\n" );
document.write( "No clowns	12	35<BR>\n" );
document.write( "Clowns	        30	8<BR>\n" );
document.write( "Perform a Z-test on nightmares after the no-clown circus minus nightmares after the clown circus. Report the test statistic.\r<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #749792 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=749792\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Your data is shown below: <BR>\n" );
document.write( "..........Nightmares	Nice dreams<BR>\n" );
document.write( "No clowns	12	35<BR>\n" );
document.write( "Clowns   	30	8<BR>\n" );
document.write( "---<BR>\n" );
document.write( "p1 = 12/47<BR>\n" );
document.write( "p2 = 30/38<BR>\n" );
document.write( "----<BR>\n" );
document.write( "Perform a Z-test on nightmares after the no-clown circus minus nightmares after the clown circus. Report the test statistic.<BR>\n" );
document.write( "---<BR>\n" );
document.write( "Ho:: p1-p2 = 0<BR>\n" );
document.write( "Ha:: p1-p2 # 0<BR>\n" );
document.write( "-----<BR>\n" );
document.write( "Sample difference:: 12/47-30/38 = -0.534 <BR>\n" );
document.write( "Standard deviation = sqrt[(12/47)(25/47)/47 + (30/38)(8/38)/38] <BR>\n" );
document.write( "= sqrt[0.0029+0.0044] = 0.0853<BR>\n" );
document.write( "---<BR>\n" );
document.write( "Test Statistic:: z(-0.534) = -0.523/0.0853 = -6.132<BR>\n" );
document.write( "----\r<BR>\n" );
document.write( "\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );