Question

2. A researcher is testing the effect of a new cold and flu medication on reaction time. A sample of n 16 students is obtained and each student is given the normal dose of the medicine. Thirty minutes later, each student's reaction time is measured. The scores for the sample averaged 3. A biopsychologist studies the role of the brain chemical serotonin in aggression. One sample of rats serves as a control group and receives a placebo. A second sample of rats receives a drug that lowers brain levels of serotonin. Then the researcher tests the animals by recording the number of aggressive responses each of the rats display. The data are presented below. Does the drug have a significant effect on aggression? Use an alpha level of 05, two fails Low Serotonin n=6 M = 22 SS - 108 Control n8 M = 14 SS = 180

please show how you arrive at the answer

Answer 1

3)

Ho :   µ1 - µ2 =   0                  
Ha :   µ1-µ2 ╪   0                  
                          
Level of Significance ,    α =    0.05                  
                          

difference in sample means =    x̅1-x̅2 =    22.0000   -   14.0   =   8.000  
                          
pooled std dev , Sp=   √([SS1 + SS2]/(n1+n2-2)) =    4.8990                  
std error , SE =    Sp*√(1/n1+1/n2) =    2.6458                  
                          
t-statistic = ((x̅1-x̅2)-µd)/SE = (   8.0000   -   0   ) /    2.65   =   3.02
                          
Degree of freedom, DF=   n1+n2-2 =    12                  
p-value =        0.0106 (excel function: =T.DIST.2T(t stat,df) )              
Conclusion:     p-value <α , Reject null hypothesis                      
                          
There is enough evidence that there is a significant effect