So what is this famous Bell Shape Curve ? Well it is has the "mean" or average in the middle and then it spreads out according to the standard deviation.
Lets say we have three class. Class A has scores of 100,90,80,70,60. Class B has scores of 100,100,80,60,60. And Class C has scores of 80,80,80,80,80.
Now if you were to find the "mean" or average of these classes they all have an 80 average. And if you were to find the "medium" or middle score, that would be 80 too. So some administrator who is not looking at the raw scores might concluded that these three classes are all the same.
But these three classes are not the same. Class B has two 100's and therefore two students who are not being challenged. Class B also has two 60's and therefore two students who are not catching onto the concepts being taught.
For Class C it looks like they took a "class test" or the teacher was sleeping during the testing.
Which brings us to the idea of why do we have grades to begin with. Most people think grades are to show how much the students have learned. But grades are not for that, they are distinguish one student from another.
That is why in education we like Class A distribution of grades 100,90,80,70,60.
So since the mean and medium are the same for these three classes we need another type of measurement. We want to know how the grades vary from each other. Or how they deviate. So we figure out a measurement called "standard deviation" or SD.
Most calculators or laptops have programs that can figure out the SD for a set of numbers. We no longer memorize these complicated formulas like we used to.
Lets look at our SAT scores. The national average is 1000 with a SD of 200.
The beauty of the Bell Shape Curve is that it can be used to show that 95% of the population of high school kids who take the SAT's are within 2 SD of the mean.
That means that 95% of the population scores somewhere from 600 to 1400 on the SAT's.
And that the only thing the SAT's can measure is that if you score somewhere between 600 and 1400 on the SAT, you are consider a "normal" student going to college.
By the way, research has shown that SAT scores is NOT a good predictor of how a student will do in college.
Another example is the IQ test. It takes your mental age and divides it by your biological age. So a 10 year old measuring with a 10 year old mentality would be 10/10 = 100.
Again we would have a standard deviation (SD) of 20, therefore 95% of the people are 2 SD away from the mean. In this case that would be 95% of the people would score somewhere between 60 and 140 on the IQ test.
And the only thing the IQ test can measure is that if you score somewhere between 60 and 140 you are considered to be have "normal" mentality.
Research has also shown that IQ test is NOT a good predictor on how a student will do in high school.
Tuesday, March 22, 2011
Monday, March 21, 2011
The SAT's
So people want to know, do the SAT scores count to get into college ? The answer is YES !! Are they more important than the gpa ? The answer is again, YES !!
Why ?
Well I am sure you have heard about grade inflation. It started in the 1970's and really did not go into effect into the 1980's when schools were worried about students self esteem. Now a days an A at one school does not mean the same as an A at another school, even in the same region of the country. And an A in the northeast does not mean the same an A in the South or West.
A recent survey of parents revealed that 80% of the parents THOUGHT their child was in the TOP 20% of their school, because they were straight A students.
In addition, schools now have 3 or 4 tracks for students to follow: there is the traditional track, the honors track, the accelerated track and the college prep track. Whatever all those tracks mean.
So you see colleges can not depend on a students gpa (grade point average) from high school. (interesting note: the gpa is still a better predictor on how a freshman will do in college than the SAT scores).
So how did the whole SAT thing get started. It was first introduced by the schools in the northeast to keep the immigrants that were coming from Europe in the early 1900's. Then it became more popular after WWII when the GI Bill was passed. Again the northeastern schools did not want farmers wondering their hallways. Research shows that these GI's actually succeeded as well or better than the normal high school kid because they took their studies seriously.
Final with grade inflation of the 1970's and 1980's and 50% of the population trying to go to college, the SAT became King.
Lets say you are big State College and your football team has just won a couple of national titles and everyone want to go to that school. Now there are 50,000 applicants but only 8,000 available spots. The easiest way to reduce that 50,000 is to punch the students SAT scores into a computer and sort. You can reject the 30,000 students who earned less than 1200 on the SAT's. They can apply at other States schools who have plenty of seats still available.
There is also the community college schools where SAT's are not even required for admissions. So every one in America gets a chance.
Why ?
Well I am sure you have heard about grade inflation. It started in the 1970's and really did not go into effect into the 1980's when schools were worried about students self esteem. Now a days an A at one school does not mean the same as an A at another school, even in the same region of the country. And an A in the northeast does not mean the same an A in the South or West.
A recent survey of parents revealed that 80% of the parents THOUGHT their child was in the TOP 20% of their school, because they were straight A students.
In addition, schools now have 3 or 4 tracks for students to follow: there is the traditional track, the honors track, the accelerated track and the college prep track. Whatever all those tracks mean.
So you see colleges can not depend on a students gpa (grade point average) from high school. (interesting note: the gpa is still a better predictor on how a freshman will do in college than the SAT scores).
So how did the whole SAT thing get started. It was first introduced by the schools in the northeast to keep the immigrants that were coming from Europe in the early 1900's. Then it became more popular after WWII when the GI Bill was passed. Again the northeastern schools did not want farmers wondering their hallways. Research shows that these GI's actually succeeded as well or better than the normal high school kid because they took their studies seriously.
Final with grade inflation of the 1970's and 1980's and 50% of the population trying to go to college, the SAT became King.
Lets say you are big State College and your football team has just won a couple of national titles and everyone want to go to that school. Now there are 50,000 applicants but only 8,000 available spots. The easiest way to reduce that 50,000 is to punch the students SAT scores into a computer and sort. You can reject the 30,000 students who earned less than 1200 on the SAT's. They can apply at other States schools who have plenty of seats still available.
There is also the community college schools where SAT's are not even required for admissions. So every one in America gets a chance.
A Little Statistics
Not too sure why so many people get scared when they hear the word statistics. It is all around us. Most of the time it is being misused. Like the famous "Bell Shape Curve" and the SAT tests for college admissions.
In fact the Curve was so misused in the 1960's that it eventually got replaced by the "box-whisker". The box-whisker is how the PSAT, SAT and college admissions office report their statistics these days.
The BW (box-whisker) gives you 5 pieces of information:
1. lowest score
2. the first quartile which is the bottom 25% of the population
3. the medium which is the middle grade
4. the third quartile which is the top 25% (or the bottom 75% if you prefer)
5. highest score
people in general understand this kind of ranking better than the Curve.
An example of the the BW would be looking at the SAT scores of an incoming freshman class, a college might report a medium of 1,000 (the middle score of the incoming freshman class at this particular school is 1,000 usually something close to 500 on the verbal and 500 on the math)
the bottom 25% might score only 800 or lower and the top 25% might score 1200 or higher.
Now remember when looking at any Stat...there are liars, there are dam good liars and then there are statisticians.
Many colleges including the State schools in Florida will do not count "special students" in their stats...this might be students where English is a second language or the football team. Most colleges also do not include students who are required to go to summer school before being admitted in the Fall.
This is ok and common practice as long all schools do it and the public is aware of it. Now YOU are !!
Also remember that the SAT's were "re-center" in the mid 1990's...the national average had dipped down to only 800....so they added 200 pts to bring it back to 1000. Your parents SAT scores do not have the same meaning as your SAT scores. I will discuss more on this in my next blog on the SAT's and its history.
In fact the Curve was so misused in the 1960's that it eventually got replaced by the "box-whisker". The box-whisker is how the PSAT, SAT and college admissions office report their statistics these days.
The BW (box-whisker) gives you 5 pieces of information:
1. lowest score
2. the first quartile which is the bottom 25% of the population
3. the medium which is the middle grade
4. the third quartile which is the top 25% (or the bottom 75% if you prefer)
5. highest score
people in general understand this kind of ranking better than the Curve.
An example of the the BW would be looking at the SAT scores of an incoming freshman class, a college might report a medium of 1,000 (the middle score of the incoming freshman class at this particular school is 1,000 usually something close to 500 on the verbal and 500 on the math)
the bottom 25% might score only 800 or lower and the top 25% might score 1200 or higher.
Now remember when looking at any Stat...there are liars, there are dam good liars and then there are statisticians.
Many colleges including the State schools in Florida will do not count "special students" in their stats...this might be students where English is a second language or the football team. Most colleges also do not include students who are required to go to summer school before being admitted in the Fall.
This is ok and common practice as long all schools do it and the public is aware of it. Now YOU are !!
Also remember that the SAT's were "re-center" in the mid 1990's...the national average had dipped down to only 800....so they added 200 pts to bring it back to 1000. Your parents SAT scores do not have the same meaning as your SAT scores. I will discuss more on this in my next blog on the SAT's and its history.
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