Question

THC	PLACEBO
6	4
5	2
3	4
6	8
9	1
3	5
4	4
7	3
6	5
2	7
6	4
7	3
5	6
6	5

A researcher is interested in determining if THC affects short-term memory. He randomly assigns 28 participants to receive either a THC pill or a placebo before completing a memory test. Perform the appropriate t test with α = .05 to find out.

a. In Excel, Calculate tobt by creating a spreadsheet formula and use the TTEST function to determine p

b. In Excel, Create a bar graph depicting the means for the two experimental groups (with estimated standard error of the mean error bars displayed).

c. Insert a textbox reporting your statistical and research conclusion in words.

Answer 1

Given that,
mean(x)=5.3571
standard deviation , s.d1=1.8649
number(n1)=14
y(mean)=4.3571
standard deviation, s.d2 =1.8649
number(n2)=14
null, Ho: u1 = u2
alternate, H1: u1 != u2
level of significance, α = 0.05
from standard normal table, two tailed t α/2 =2.16
since our test is two-tailed
reject Ho, if to < -2.16 OR if to > 2.16
we use test statistic (t) = (x-y)/sqrt(s.d1^2/n1)+(s.d2^2/n2)
to =5.3571-4.3571/sqrt((3.47785/14)+(3.47785/14))
to =1.42
| to | =1.42
critical value
the value of |t α| with min (n1-1, n2-1) i.e 13 d.f is 2.16
we got |to| = 1.41871 & | t α | = 2.16
make decision
hence value of |to | < | t α | and here we do not reject Ho
p-value: two tailed ( double the one tail ) - Ha : ( p != 1.4187 ) = 0.18
hence value of p0.05 < 0.18,here we do not reject Ho
ANSWERS
---------------
null, Ho: u1 = u2
alternate, H1: u1 != u2
test statistic: 1.42
critical value: -2.16 , 2.16
decision: do not reject Ho
p-value: 0.18
we do not have enough evidence to support the claim that difference of means between Thc and placebo.
standard error = standard deviation /sqrt(n)
standard error = 1.8649/sqrt(14)
standard error = 0.4984
for both thc and placebo same standard error because they have standard deviation and sample size.