```Date: Tue, 29 Mar 2005 11:07:16 -0800 Reply-To: cassell.david@EPAMAIL.EPA.GOV Sender: "SAS(r) Discussion" From: "David L. Cassell" Subject: Re: Correlation between MAT Score v/s GPA Comments: To: srihari swamynathan In-Reply-To: <20050329013037.29050.qmail@webmail29.rediffmail.com> Content-type: text/plain; charset=US-ASCII srihari swamynathan replied: > On Tue, 29 Mar 2005 David L.Cassell wrote : > >I see that Wensui Liu has already given you some excellent advice. > > > >Depending on what your hypothesis really is, PROC CORR may be the > >answer, and it may not. What do you mean? Here are three different > >options you might be contemplating. Note that they are VERY different! > > > >1 "MAT and GPA rise together linearly." > >2 "MAT and GPA rise together, but not necessarily linearly." > >3 "If MAT goes up, then GPA goes up too." > > > >Option 1 is a linear correlation. This looks like PROC CORR with > >Pearson correlation. > > > >Option 2 is a monotonic relationship. As Wensui noted, now you're > >into the realm of Spearman correlations. > > > >Option 3 is not correlation at all, but causality. You CANNOT conclude > >this using correlations. In fact, you cannot attribute causality using > >only statistics, no matter what. > > > >So again I ask, what do you mean? What is your underlying hypothesis? > > well, my hypothesis is to show that the MAT score has a significant > effect on GPA. In simpler terms, one who is scoring good marks in > MAT has a higher GPA than who doesnt have. I'm sorry, but you need to quantify that a bit more. Can you state your hypothesis numerically? Statistically? Are you assuming causality or not? Your response is still too vague for me to tell *exactly* what you mean. David -- David Cassell, CSC Cassell.David@epa.gov Senior computing specialist mathematical statistician ```

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