correlation between two arrays

[Imano88]

hello,

please i need help in labview. i have collected data in stabilometer and i determined the area and circumference of XY graph for 30 staudents before and after carrying a backpack, so I want to enter the values of the area for the 30 students before and after and do the correlation between them and plot the variation nd the same thing will be done for the circumference.

Any Help Please !!! 

[johnsold]

There are several correlation VIs in the Mathematics >> Probablilty and Statistics palette. Have you tried these? If they do not work, please be as specific as possible in explaining what you expect and why it does not seem to work for you.  Posting your VI along with some typical data is also very helpful.  (Please do not send the backpacks! We do not want to become additonal test subjects.)

Lynn

[altenbach]

You are talking about a very specialized discipline, but don't tell us what the x and y axis are and what they represent. The raw output of a stabilometer can be shown in may differnt ways. I searched the web a little bit and I am wondering if you are talking about a "stabilogram", e.g. as shown here on the left.

So you want the area and the circumference from each dataset. I guess you already worked out the algorithms to extract those from the graph?

"Correlation" is a bit of a generic word they way you are using it. How should they be correlated? Do you want to create new xy graphs, where each point is a subject and x is the area (or circumference) without backpack and y with backpack? Do you expect a linear correlation and want the correlation coefficient, for example, or is the dependency something more complicated (e.g. higher order polynomial). Can you show us some typical data?

[Imano88]

here is my code ... the stabilometer is a device that measures the balance ... in each measurment I have two txt file to save the data which are X and Y where X is the movement of the body to the right and left and Y is the anterior-posterior movement, I have attached the two txt files in the name XB and YB where B means at the begining before the student walk a distance with a backpack , also I extract XE and YE which means the stabilometer measurement after the student walk with a backpack to check if there is any influence of that load on the student's balance... in the code I plot XB in terms of YB and I draw a circle on the XY grpah to calculate the area and circumference, and the same thing will be done with XE and YE... and that will be done for 30 students... So I want to plot the area ( for XB and YB ) for all students by putting the values of the area for each student in an array , and also I want to plot the area (XE and YE) for all the student by putting all the area values in an array and see the difference ... and that will be done using the correlation between them ( between the begining (B) and the end (E) )