Answer:
See the attachment for formatted formulas
Step-by-step explanation:
Let X11, X12, ……,X1n and X21 , X22……., X2n be two small independent random samples from two normal populations with means u1 and u2 and the standard deviations σ1 and σ2 respectively. If σ1= σ2 (=σ) but unknown then the unbiased pooled or combined estimate of the common variance σ2 (the term variance means that each population has the same variance) is given by
Sp2 = ((n_1-1) s_(1^2 )+ (n_2-1) s_2^2)/(n_1+n_2-2)
Where
S12 = 1/(n_1- 1) ∑▒〖 (X_1i- X`_1)〗^2 and
S22 = 1/(n_2- 1) ∑▒〖 (X_2j- X`_2)〗^2
The test statistic
t = ((X_1`-X_2`)- (μ_1- μ_2))/(√(s_p&1/n_1 )+ 1/n_2 )
Has t distribution with v= n1 + n2 – 2 degrees of freedom.
It is used as a test statistic for testing hypotheses about the difference between two population means.
The procedure for testing hypothesis H0: μ_1- μ_2= ∆_0 in case of small independent samples when σ_1= σ_2 is as follows.
- Formulate the null and alternative hypotheses given σ_1= σ_2= σ unknown.
H0: μ_1- μ_2= ∆_0 against the appropriate alternative.
- Decide the significance level α.
- The test statistic under H0 is
t = ((X_1`-X_2`)- ∆_0 )/(√(s_p&1/n_1 )+ 1/n_2 )
Which has t distribution with v= n1 + n2 – 2 degrees of freedom.
- Identify the critical region
- Compute the t- value from the given data
- Reject H0 if t falls in the critical region, accept H0 otherwise.
