Difference between revisions of "Manuals/calci/FTEST"

Revision as of 02:01, 10 December 2013

FTEST(ar1,ar2)

This function gives the result of F-test.
The F-test is designed to test if two population variances are equal.
It does this by comparing the ratio of two variances.
So, if the variances are equal, the ratio of the variances will be 1.Let X1, ..., Xn and Y1, ..., Ym be independent samples each have a normal distribution .
It's sample means: X(bar)=1/n summation(i=1 to n)Xi and Y(bar)=1/m summation(i=1 to m)Yi .
The sample variances : Sx^2=1/n-1 summation(i=1 to n)(Xi-X(bar))^2.and SY^2=1/m-1 summation(i=1 to m)(Yi-Y(bar))^2.
Then the test statistic= Sx^2/Sy^2 has an F-distribution with n − 1 and m − 1 degrees of freedom.
In FTEST(ar1,ar2) where ar1 is the data of first array,ar2 is the data of second array.
The array may be any numbers, names, or refernces that contains numbers.
Suppose the array contains any text, logical values or empty cells like that values are not considered.

When the ar or ar2 is less than 2 or the variance of the array value is zero then this function will return the result as error.

1.DATA1 DATA2

 15                   21
  27                  12
  19                  30
 32                    11

FTEST(B4:B8,C4:C8)=0.81524906747183 2.DATA 1={5,8,12,45,23}; DATA2={10,20,30,40,50}

FTEST(A1:A5,C1:C5)=0.9583035732212274

3. DATA1={14,26,37};DATA2={45,82,21,17} FTEST(B1:B3,C1:C4}=0.26412211240525474 4.DATA1={25},DATA2={45,65} FTEST(B1,C2:C3)=NAN

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 ==Examples==
-#Find the correlation coefficients for X and Y values are given below :X={1,2,3,4,5};  Y={11,22,34,43,56}
+.DATA1          DATA2
-=CORREL(A4:A8,B4:B8)=0.99890610723867
+                   21
-#The following table gives the math scores and times taken to run 100 m for 10 friends:SCORE(X)={52,25,35,90,76,40}; TIME TAKEN(Y)={11.3,12.9,11.9,10.2,11.1,12.5}
+                  12
-=CORREL(A5:A10,B5:B10)= -0.93626409417769
+                  30
-#Find the correlation coefficients for X and Y values are given below :X={-4,11,34,87};Y={9,2,59,24}
+                    11
-=CORREL(A1:A4,B1:B4)=0.353184665607273
+FTEST(B4:B8,C4:C8)=0.81524906747183
+.DATA 1={5,8,12,45,23};  DATA2={10,20,30,40,50}
+ FTEST(A1:A5,C1:C5)=0.9583035732212274
+. DATA1={14,26,37};DATA2={45,82,21,17}
+FTEST(B1:B3,C1:C4}=0.26412211240525474
+.DATA1={25},DATA2={45,65}
+FTEST(B1,C2:C3)=NAN
 ==See Also==