<p>Hey guys i have question about standard deviation for test scores since im not too sure how to interpret it. I know what it is just not how to see how well i did. If the average for my test was a 66.6 and i got 85.25, what would that tell me about how i did compared to others or my ranking in the class or would it? Thanks a bunch</p>
<p>Depends on the standard deviation.</p>
<p>The average is usually considered to be a B-, and 1 standard deviation above that would equate to an A-, while 1 standard deviation below that is a C-.</p>
<p>Let's say the standard deviation was 15, then your score of 85 would be a little above 1 standard deviation away (81.6), which would give you an A- to A grade. </p>
<p>Hopefully that makes sense.</p>
<p>ok thanks! Oh i forgot to say that he sd was 15 and the class is curved to a B-, but like 12-15% get A's.</p>
<p>One standard deviation usually equals one letter grade. :rolleyes:</p>
<p>from Wikipedia, "n practice, one often assumes that the data are from an approximately normally distributed population. If that assumption is justified, then about 68% of the values are within 1 standard deviation of the mean, about 95% of the values are within two standard deviations and about 99.7% lie within 3 standard deviations."</p>
<p>So the top 16% is 1 std dev. above the mean. You're a little more than 1 std dev. above the mean, so likely an A by the numbers you gave. If you look up a stats chart you can convert your score in std deviation to a percentile, assuming a normal curve for scores.</p>