Linear Regression Equation

#1
Dear friends,
I have a set of data as follows:
1....... 58.82±3.23
10....... 62.5±7.90
50....... 87.23±2.33
100....... 110.29±10.33
200....... 84.56±8.67

I have the linear regression equation for the above data, which is y=50.2530+0.2822x and correlation coefficient (r) as 0.5858. But the problem is that I don;t know how to reach this equation and r from the above mentioned data.

Any help will be highly appreciated.

~Regards
Pavnesh
 
E

elnaz

Guest
#2
Hello
the first please tell me about your data.
but you know you should have two diffrent set of data one for y another for x , then you can use of SPSS for linear regression.
please tell me about your data certainly.

Best regards
Elnaz
 
#3
Purpose of this Q: First of all, I am a non-mathematics/statistics student. I am doing Ph.D in botany. About this data: on the first column, it is the concentration of Cadmium in soil(this being done as exp in lab) and 2nd column is the plant height in cm. Since this experiment was done in triplicates, so the second set have the values of the form average±Standard Deviation.E.g. 58.82 is the av and 3.23 is SD. Here 58.82 is the average plant height of the three plants at the same concentration. And then SD was calculated. Data is again for your reference.

1....... 58.82±3.23
10....... 62.5±7.90
50....... 87.23±2.33
100....... 110.29±10.33
200....... 84.56±8.67

The linear regression equation mentioned earlier was y=50.2530+0.2822x and correlation coefficient (r) = 0.5858. But the problem is that I could not reach the above equation. I used Microsoft excelsheet (ME) to find out the equation. But ME could not understand this data. When I removed SD from the data and tried to find out the equation, then it came out to be y=50.899+9.927x and r = 0.7519, which is nowhere near to the desired equation.

In case if you feel that still the information which I provided is not suficient, then let me know.

I appreciate your efforts in helping me. Thanks a lot in advance.

Regards,
Pavnesh
 
E

elnaz

Guest
#4
Hello
thanks , if i understood true you have two colunm and you know it's true equ of linear regression but you did it by a sotware that you couldnot reach to this equ. did i understand true?
i think your software is not good or your above equ is not true .
no problem i do it by SPSS that i can check your answer
but for final Q : why dont you sum your data in second colunm?
Best regards
Elnaz
 
#5
Dear Elnaz,
Thanks for your precious time. In order to get the sum of 2nd column, then I have to remove the SD. If do that, then I get altogether a different equation (with MS excelsheet) and even I tried to find the eqn doing the calculations manually, I reach at the same equation. now I am confused, which one is correct.

I am worried about this because there are a lot of such equations in my thesis and if I do wrong one, then all be done in the same way and hence wrong. So it will make my thesis less relevant and I will be in trouble in front of examiners when presenting my reseach.

I hope u understand my concern.

If you reach at any conclusion, I would really appreciate if you could give me the details steps.

Regards,
Pavnesh
 
E

elnaz

Guest
#6
Hello
excuse me i am confused a little that why does your second column have two number , one with summation sign another with minus sign .
please tell me about it and if possible represent your data very clearly e.g obtain independent and dependent variable and the number of your variable e.g 2 0r 3 variable.

Best regards
Elnaz