For 2sample t, the hypotheses are as follows.
 Null hypothesis

H_{0}: μ_{1} – μ_{2} = δ_{0} 
The difference between the population means (μ_{1} – μ_{2}) equals the hypothesized difference (δ_{0}). 
 Alternative hypothesis
 Select one of the following alternative hypotheses.
H_{1}: μ_{1}– μ_{2}≠ δ_{0} 
The difference between the population means (μ_{1} – μ_{2}) does not equal the hypothesized difference (δ_{0}). 
H_{1}: μ_{1}– μ_{2}> δ_{0} 
The difference between the population means (μ_{1} – μ_{2}) is greater than the hypothesized difference (δ_{0}). 
H_{1}: μ_{1}– μ_{2}< δ_{0} 
The difference between the population means (μ_{1} – μ_{2}) is less than the hypothesized difference (δ_{0}). 