Student’s t Test

This is the most frequently used tools in statistical analysis for comparing the experimental method with means. This tools assist in analyzing confidence interval that is the range in which the true value might fall within a given probability.  This range limit is known as confident limit. The probability that true value may fall within the range is known as probability of confident level, it often express in percentage.

The calculation of statistical t-value is done and the similarity with the tabulated t-value are compared. So when the t-value is above the tabulate t-value, then there are significant different between the two experimental procedure at the confident levels. But if it did not exceed, then we assumed that there are no significant different between the two procedures.

There are three way of using student t-test, which are;

1. T-test are used when true value is known
2. T-test in comparing a replicate measurement
3. T-test in comparing individual difference.

T-test when standard or true value is known

Mathematically

±t = ( x – μ) √N/S

X = means value

μ = true value

N = number of observation

S = standard deviation

T-test in comparing a replicate measurement

 

                         n1 + n2 K
SP = √(x1i  X1)2 + (x2i – x2)2 + (xki xk)2

x1, x2, ………xn are means value of each set.

Sp = pooled standard deviation

Xi1, Xi2,…….Xik = individual value set

K = sets of analyses

T-test in comparing individual difference

This method is applied when we use two different procedure to make single measurement on a varieties of different samples. No duplicative measurement.

         D

T  = ———   √n

        Sd

Sd = √(di, d)2/n 1

di = individual different between two methods for each sample with regards to sign

d = individual difference of all means