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    <title>topic Comparing means before and after study entry - need insight in SAS Procedures</title>
    <link>https://communities.sas.com/t5/SAS-Procedures/Comparing-means-before-and-after-study-entry-need-insight/m-p/115603#M31958</link>
    <description>&lt;HTML&gt;&lt;HEAD&gt;&lt;/HEAD&gt;&lt;BODY&gt;&lt;P&gt;Hello,&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;I need to compare means before and after study entry to see if there is a statistically significant difference between the two, and am wondering what the best way would be to evaluate this? I wanted to do logistic regression; however am unsure how to set this up.&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;I need to do this for three separate models: ER visits, Hospital visits and Jail visits - and need to see if the average visits is different before and after study entry (in order to assess impact of treatment/counseling on these visits).&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;Here is how the means are setup:&lt;/P&gt;&lt;P&gt;proc means data=CostDrivers;&lt;/P&gt;&lt;P&gt;var ERDAYS_PRE_4 ERDAYS_PRE_3 ERDAYS_3 ERDAYS_4;&lt;/P&gt;&lt;P&gt;var HOSPDAYS_PRE_4 HOSPDAYS_PRE_3 HOSPDAYS_3 HOSPDAYS_4;&lt;/P&gt;&lt;P&gt;var JAILDAYS_PRE_4 JAILDAYS_PRE_3 JAILDAYS_3 JAILDAYS_4;&lt;/P&gt;&lt;P&gt;run;&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;ERDAYS_PRE_4 = 12 months before study entry whereas ERDAYS_4 = 12 months POST study entry.&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;Any ideas?&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;Thanks!&lt;/P&gt;&lt;/BODY&gt;&lt;/HTML&gt;</description>
    <pubDate>Fri, 21 Jun 2013 18:51:47 GMT</pubDate>
    <dc:creator>SASstudent2013</dc:creator>
    <dc:date>2013-06-21T18:51:47Z</dc:date>
    <item>
      <title>Comparing means before and after study entry - need insight</title>
      <link>https://communities.sas.com/t5/SAS-Procedures/Comparing-means-before-and-after-study-entry-need-insight/m-p/115603#M31958</link>
      <description>&lt;HTML&gt;&lt;HEAD&gt;&lt;/HEAD&gt;&lt;BODY&gt;&lt;P&gt;Hello,&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;I need to compare means before and after study entry to see if there is a statistically significant difference between the two, and am wondering what the best way would be to evaluate this? I wanted to do logistic regression; however am unsure how to set this up.&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;I need to do this for three separate models: ER visits, Hospital visits and Jail visits - and need to see if the average visits is different before and after study entry (in order to assess impact of treatment/counseling on these visits).&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;Here is how the means are setup:&lt;/P&gt;&lt;P&gt;proc means data=CostDrivers;&lt;/P&gt;&lt;P&gt;var ERDAYS_PRE_4 ERDAYS_PRE_3 ERDAYS_3 ERDAYS_4;&lt;/P&gt;&lt;P&gt;var HOSPDAYS_PRE_4 HOSPDAYS_PRE_3 HOSPDAYS_3 HOSPDAYS_4;&lt;/P&gt;&lt;P&gt;var JAILDAYS_PRE_4 JAILDAYS_PRE_3 JAILDAYS_3 JAILDAYS_4;&lt;/P&gt;&lt;P&gt;run;&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;ERDAYS_PRE_4 = 12 months before study entry whereas ERDAYS_4 = 12 months POST study entry.&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;Any ideas?&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;Thanks!&lt;/P&gt;&lt;/BODY&gt;&lt;/HTML&gt;</description>
      <pubDate>Fri, 21 Jun 2013 18:51:47 GMT</pubDate>
      <guid>https://communities.sas.com/t5/SAS-Procedures/Comparing-means-before-and-after-study-entry-need-insight/m-p/115603#M31958</guid>
      <dc:creator>SASstudent2013</dc:creator>
      <dc:date>2013-06-21T18:51:47Z</dc:date>
    </item>
    <item>
      <title>Re: Comparing means before and after study entry - need insight</title>
      <link>https://communities.sas.com/t5/SAS-Procedures/Comparing-means-before-and-after-study-entry-need-insight/m-p/115604#M31959</link>
      <description>&lt;HTML&gt;&lt;HEAD&gt;&lt;/HEAD&gt;&lt;BODY&gt;&lt;P&gt;I think you need to provide some more information regarding the experimental design.&lt;/P&gt;&lt;P&gt;&lt;/P&gt;&lt;P&gt;From what you have I don't see why 3 t-tests or 3 anova's wouldn't be appropriate.&lt;/P&gt;&lt;/BODY&gt;&lt;/HTML&gt;</description>
      <pubDate>Fri, 21 Jun 2013 19:07:27 GMT</pubDate>
      <guid>https://communities.sas.com/t5/SAS-Procedures/Comparing-means-before-and-after-study-entry-need-insight/m-p/115604#M31959</guid>
      <dc:creator>Reeza</dc:creator>
      <dc:date>2013-06-21T19:07:27Z</dc:date>
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