Question

Annie wants to test whether or not drinking coffee will immediately increase heart rate while sitting in class. Six people measured their heart rates before drinking coffee and then the same six people took their heart rates after drinking their coffee. Please calculate the t-statistic for this experiment; then state the critical value; then come to a conclusion concerning the null hypothesis; and then state what the implications are concerning drinking coffee.

No Coffee                   Coffee

79                                  84

71                                  78

84                                  87

66                                  75

74                                  80

76                                  82

Answer 1

	No coffee	Coffee	Diff = After - Before
	79	84	5
	71	78	7
	84	87	3
	66	75	9
	74	80	6
	76	82	6
Mean		Dbar	6
SD		SD	2

n = 6

Let α=0.05

Hypothesis:

Ho: μD​ = 0

Ha: μD​ ≠ 0

Test:

t stat = Dbar/(SD/SQRT(n)) = 6/(2/SQRT(6)) = 7.3485

Critical value:

α=0.05, df = n-1 = 5

tc = 2.571 (Use t table)

Conclusion:

t stat > t critical, Reject H0

P value = 0.0007 < 0.05, Reject H0

There is enough evidence to conclude that drinking coffee will immediately increase heart rate while sitting in class