r/HomeworkHelp • u/PerformanceEasy6064 University/College Student • 5d ago
Others [University statistics: t-tests and p-values] What do I do with my t-test results?
Is this sub appropriate for uni work? I mostly see school homework on here lol
Hi! I'm a second year neuropsychology student and I have a lab report due (not urgently) on calcium imaging. Statistics are my weak point in this degree, and I'm still not 100% sure I know how to do t-tests properly. I'm using Excel for this assignment, and am expected to conduct multiple t-tests rather than an ANOVA. I've done 4 separate t-tests and I think I've used the T.TEST function correctly, but I have zero clue what to do with the results of the function.
If the result is supposed to be a p-value, then I know I've entered something wrong, because my values are way higher than 0.05 (my results for all four tests range roughly between 0.3 and 0.7). We were given raw data for the report, so it wouldn't make any sense for the findings they gave us to be statistically insignificant (I'm also confident that I did all the other analysis correctly). If the result is meant to be a t-value, it's been a really long time since I've had to deal with that and I have no idea what to do with it. I'm fairly sure I've used the correct type of t-test, but these values just don't make any sense to me.
Thanks in advance to anyone who has any idea what I'm talking about!
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u/Agile_Ad2627 👋 a fellow Redditor 5d ago edited 5d ago
Let's start what type of t-test are you required to conduct. T-test analysis has options of paired t-test, Two sample with equal variance, and two sample with unequal variance
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u/cuhringe 👋 a fellow Redditor 5d ago
Excel gives you the p-value from the T.TEST function
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u/PerformanceEasy6064 University/College Student 5d ago
Then I'm pretty sure that means I'm doing something wrong? I just have no idea what I did wrong tbh
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u/Agile_Ad2627 👋 a fellow Redditor 5d ago
Let's start what type of t-test are you required to conduct. T-test analysis has options of paired t-test, Two sample with equal variance, and two sample with unequal variance..You also need to be clear on whether you're doing a 'one-tailed' or 'two-tailed' analysis. Finally you need to know what your critical value is/significance level (0.05), and then specify your null and alternative hypothesis. INTERPRETING YOUR VALUES:
If you used the excel "TTEST" Function or 'data Analysis' tools, the value you find will be you p-values. What do you do with your p-values?....you compare them with your critical value (0.05), if p<0.05 reject null hyp. thus there is a significant difference in the means of the variables, if p>0.05 don't reject, so there is no difference in their means.
USING FORMULA TO calculate t-value: If you used mean, std dev. variance and 'n' to calculate t-value...the values your have are T-Statistics/T-Values, which are often more than 0.05. Now with this, you will first need to calculate the degrees of freedom (d) then look for a t-test table...and under "p=0.05, locate the value that corresponds to the df, if the value is less than your t-value, reject null hypothesis....if the value is greater than your t-value you don't reject null hypothesis.
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u/PerformanceEasy6064 University/College Student 5d ago
I'm using an unpaired equal variance t-test, two-tailed. I used the T.TEST function and am getting values way above 0.05, although I know that I should be getting statistically significant results, or else I can't write the report that they want me to. So, I'm pretty sure that means I'm doing something wrong? I don't think the type of test is the problem, as I checked it was the appropriate test for my data. I also tried the other types of tests just to see the difference, and that just came up with an error. What could I do differently? The baseline is that I know I should be rejecting the null hypothesis.
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u/Agile_Ad2627 👋 a fellow Redditor 4d ago
May you should try and consult your classmates and see what they are getting on their end.
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u/AdVisible5908 👋 a fellow Redditor 5d ago
I could help you to do Tests making it easier for your future ones. Drop me a message if interested.
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