T test calculator is used to calculate a statistical hypothesis test where the test statistic follows a students t distribution. This is done only when the null hypothesis is supported. t = (mean(x1) – mean(x2)) / √ (s12/n1 + s22/n2)
= difference between means of 2 samples/ (variance / sample size).
Example 1: Using t test calculator solve the following;
X1 = 2,4,6,8 ; X2 = 3,6,9,12
Mean of x1 = 2+4+6+8/4= 20/4=5
Mean of x2= 3+6+9+12/4= 30/4 =7.5
Standard deviation for x1
1. Sum (x1-mean x1)2 = (2-5)2+(4-5)2+(6-5)2+(8-5)2= 9+1+1+9= 20
2. Sum (x2-mean x2)2 = (3-7.5)2+(6-7.5)2+(9-7.5)2+(12-7.5)2= 20.25+2.25+2.25+20.25= 45
3. Standard deviation x1= s12= 20/4= 5
4. Standard deviation x2= s22= 45/4=11.25
T critical value
T = (mean(x1) – mean(x2))/√(s12/n1 + s22/n2)
5-7.5/√/(5/4+ 11.25/4) = -2.5/√16.25/4= -2.5/2.015 = - 1/0.4 = -1.240
Example 2: Using t test calculator solve following;
X1 = 4,5.5,2.5 ; X2 = 4.5,14
Mean of x1 = 4+5.5+2.5= 12/3=4
Mean of x2= 4.5+14/2= 18.5/2 =9.25
Standard deviation for x1
1. Sum (x1-mean x1)2 = (4-4)2+(5.5-4)2+(2.5-4)2= 0+2.25+6.25= 8.5
2. Sum (x2-mean x2)2 = (4.5- 9.25)2+(14 -9.25)2= 22.5625+22.5625= 45.125
3. Standard deviation x1= s12= 8.5/3= 2.83
4. Standard deviation x2= s22= 45.125/2=22.5625
T = (mean(x1) – mean(x2))/√(s12/n1 + s22/n2)
4-9.25/√/(2.83/3+ 22.5625/2) = -5.25/√10.33825= -5.25/3.215= - 1.632970