Question

I need Statistics help please!


a test is made of Ho: u=4 versus H1: u>4 using a sample size of 25. The population standard deviation is unknown. Find the critical value of the test statistic if the significance level is 0.05

Answer 1

Hey! Do you know how to do this?

Answer 2

any ideas from you? what do you recall a test statistic defines?

Answer 3

and it seems like there might be some information missing from your posting. a sample deviation would be helpful ....

Answer 4

That's the reason I don't know what to do.

Answer 5

hmm

i know ... usually we have some of the sample stats to play with.

z = (Ho - sample mean)/(s/sqrt(n))

if n < 30 we usually do t test with the same parameters, and look up the table under
n-1, and the significant value.

maybe, we are to look up in the t distribution under t=24, looks one tailed to me, at a=.005

Answer 6

do you have a t table?

Answer 7

http://mips.stanford.edu/courses/stats_data_analsys/lesson_4/t_table.gif

Answer 8

dF = 24, one tailed, a=.05

Answer 9

ok, yeah, the critical value is the point at which we define the rejection/acceptance boundary for the hypothesis test.

Answer 10

Yes i do have t table

Answer 11

then since our sample is 25, do you agree that we want the row for 24?

Answer 12

and since our alternate hypothesis is 'greater than" 4 .. then we are concerned with one side only .... the right side. a one tailed region

Answer 13

Yes.

Answer 14

then its just a matter of matching row and col ... and reading the feild value

Answer 15

okay but how would i put this into a formula

Answer 16

why would you need to for this question?

Answer 17

all this value does is define a boundary for us ... the actual t value we get from the test statistic will be compared to this "critical" value.

Answer 18

Wait is the t value the critical value?

Answer 19

there are 2 values we are concerned with when testing a hypothesis.

the critical value defines our region for rejection/acceptance

the critical value is like a fence in a baseball field. anything that lands beyond it, is a homerun (reject the null); anything that lands inside of it is fair play (fail to reject the null).

the actual value of our test statistic ... is where the baseball actually lands.

Answer 20

this questions asks us to define the fence line

Answer 21

what did you get from the table?

Answer 22

t=1.711

Answer 23

good, i got that as well

now, our critical value is 1.711

if the ACTUAL test statistic we calculate is more than this: t > 1.711, then we are out of bounds and we (reject the null hypothesis)

if the ACTUAL test statistic we calculate is equal to or less than this: t <= 1.711, then we are in bounds and we (fail-to-reject the null hypothesis)

Answer 24

okay thank you so much!!

Answer 25

youre welcome