Question

13. A researcher assesses 7 students on test anxiety using blood pressure as a measure (the higher the blood pressure, the greater the anxiety); she then assesses the same subjects again after they view a 2-hour videotape on "relaxation techniques under stress". The results, average systolic blood pressure, were:

Subject Before After

1 120 110

2 160 110

3 124 100

4 135 99

5 170 115

6 143 106

7 188 89   

   1. State the independent and dependent variables.
   2. State the Null Hypothesis in words and symbols.
   3. Compute the appropriate statistic.
   4. What is the decision? reject
   5. State the full conclusion in words.

Answer 1

Sample #1	Sample #2	difference , Di =sample1-sample2	(Di - Dbar)²
120	110	10.00	1185.33
160	110	50.00	31.04
124	100	24.00	417.33
135	99	36.00	71.04
170	115	55.00	111.76
143	106	37.00	55.18
188	89	99.00	2978.04

	sample 1	sample 2	Di	(Di - Dbar)²
sum =	1040	729	311.000	4849.714

Ho :   µd=   30                  
Ha :   µd ╪   30                 

Ho: DIFFERENCE OF BLOOD PRESSURE IS EQUAL BEFORE AND AFTER RELAXATION TECHNIQUE
Ha: DIFFERENCE OF BLOOD PRESSURE IS not EQUAL BEFORE AND AFTER RELAXATION TECHNIQUE   
Level of Significance ,    α =    0.05       claim:µd=0          
                          
sample size ,    n =    7                  
                          
mean of sample 1,    x̅1=   148.571                  
                          
mean of sample 2,    x̅2=   104.143                  
                          
mean of difference ,    D̅ =ΣDi / n =   44.429                  
                          
std dev of difference , Sd =    √ [ (Di-Dbar)²/(n-1) =    28.4304                  
                          
std error , SE = Sd / √n =    28.4304   / √   7   =   10.7457      
                          
t-statistic = (D̅ - µd)/SE = (   44.42857143   -   30   ) /    10.7457   =   1.343
                          
Degree of freedom, DF=   n - 1 =    6                        
                          
p-value =        0.227924   [excel function: =t.dist.2t(t-stat,df) ]               
decision p-value>α , Do not reject null hypothesis     

conclusion : DIFFERENCE OF BLOOD PRESSURE IS EQUAL BEFORE AND AFTER RELAXATION TECHNIQUE                

Please revert in case of any doubt.

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