document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1049220>Question 1049220</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Examining Relationships \r<BR>\n" );
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document.write( "Question 3<BR>\n" );
document.write( "Select one answer. <BR>\n" );
document.write( "10 points<BR>\n" );
document.write( "If there is no relationship (linear or otherwise) between two quantitative variables as observed on a scatterplot, the value of the correlation coefficient, r, is likely to be which of the following? <BR>\n" );
document.write( "•	 Closer to 1<BR>\n" );
document.write( "•	 Closer to &#8722;1<BR>\n" );
document.write( "•	 Closer to 0 <BR>\n" );
document.write( "•	 Either closer to &#8722;1 or 1\r<BR>\n" );
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document.write( "Question 4<BR>\n" );
document.write( "Select one answer. <BR>\n" );
document.write( "10 points<BR>\n" );
document.write( "Using data from 100 hospitals, a correlation of r = 0.78 is found between the size of a hospital (measured in number of beds) and the average length of patient stays (measured in days). Which of the following is true?<BR>\n" );
document.write( "•	 There is a pretty strong positive linear correlation between number of beds and length of hospital stay.<BR>\n" );
document.write( "•	 “Severity of illness” is a possible lurking variable that is behind this relationship.<BR>\n" );
document.write( "•	 Increasing hospital size must be the cause of longer patient stays. \r<BR>\n" );
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document.write( "Question 6<BR>\n" );
document.write( "Select one answer. <BR>\n" );
document.write( "10 points<BR>\n" );
document.write( "Suppose the correlation between two variables (x, y) in a data set is determined to be r = 0.63, What must be true about the slope, b, of the least-squares line estimated for the same set of data? <BR>\n" );
document.write( "•	 The slope b is always equal to the square of the correlation r. <BR>\n" );
document.write( "•	 The slope will have the opposite sign as the correlation. <BR>\n" );
document.write( "•	 The slope will have the same sign as the correlation.<BR>\n" );
document.write( "•	 The slope will also be a value between &#8722;1 and 1. \r<BR>\n" );
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document.write( "Question 7<BR>\n" );
document.write( "Select all that apply. <BR>\n" );
document.write( "10 points<BR>\n" );
document.write( "A study was done on the timeliness of flights categorized as either \"on time\" or \"delayed\" of two major airlines: StatsAir and AirMedian. Data were collected over a period of time from five major cities and it was found that StatsAir does better overall (i.e., has a smaller percentage of flights categorized as delayed). However, in each of the five cities separately, AirMedian does better (i.e., has a smaller percentage of flights categorized as delayed in each city).<BR>\n" );
document.write( "Which of the following is correct? Check all that apply.\r<BR>\n" );
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document.write( "•	 This is an example of Simpson's paradox.<BR>\n" );
document.write( "•	 \"City\" is a lurking variable in this example.<BR>\n" );
document.write( "•	 This is an example of a negative association between variables.\r<BR>\n" );
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document.write( "Question 8<BR>\n" );
document.write( "Select one answer. <BR>\n" );
document.write( "10 points<BR>\n" );
document.write( "A correlation of r = 0.85 is found between weekly sales of firewood and cough drops over a 1-year period. Which of the following is a correct interpretation of this correlation value?<BR>\n" );
document.write( "•	 Temperature is a possible lurking variable that is behind this relationship. <BR>\n" );
document.write( "•	 There is a pretty strong positive linear relationship between sales of firewood and cough drops. <BR>\n" );
document.write( "•	 Fire must be the cause of coughing. <BR>\n" );
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document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #664760 by </B><A HREF=/tutors/aboutme.mpl?userid=ikleyn><B>ikleyn(52794)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=ikleyn><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/cgi-bin/show-face.mpl?user=ikleyn><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=664760\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> .<BR>\n" );
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document.write( " </SPAN>\n" );
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