Simple t-test problem, why am I so lost

[faquewdikhed]

I am doing a study in my health and fitness class relating mens and womens VO2Max (lung capacity basically).

I think I have all of the relevant data:

n1=358, mean=38.95
n2=200, mean=44.89

When I calculate that to get my t-value, I get -3.423 for my t-value. I have no idea what this means, or how to find out. Help?
[img]/images/graemlins/confused.gif[/img]

[Siegmund]

The relevant data also include the standard deviations of each group (or one standard deviation for all the data and an argument why you believe the SD is equal in both groups.)

[Borat KGB]

When you calculate your t test value, you should also be given what type of confidence interval you're testing on. This t test value most likely falls within the critical region so your choice would be to reject the null hypothesis that there's no significant difference between the two sample means. Therefore, there is a significant difference between men's and women's VO2Max.

Have a nice day!

[ICMoney]

[ QUOTE ]
When you calculate your t test value, you should also be given what type of confidence interval you're testing on. This t test value most likely falls within the critical region so your choice would be to reject the null hypothesis that there's no significant difference between the two sample means. Therefore, there is a significant difference between men's and women's VO2Max.

Have a nice day!

[/ QUOTE ]


If a value falls outside the critical region and you reject the null hypothesis, you are stating there is a significant difference (difference between the means did not happen by chance).

[ICMoney]

Are you calculating a Z value or a T value?

A Z value is when you know the mean for the entire population.

A T value is the mean for a sample.

If you are calculating a T value, you will need to know how many are in the sample and use this number to find degrees of freedom.

You will use the Z or T value (and degress of freedom for T) to calculate the critical value for a 1- or 2- tail test.

You will need to look in a statistical table or use Excel to find the critical value.

95% confidence is usually the default.
.025 proportion in one tail or .05 in two tails combined.

Hope that makes sense.

[ICMoney]

A good stats resource is:

Stat Workshop - Psych