t-test

  1. N

    F-test for two-tailed vs. one-tailed

    Goal: Determine if two sample sets are "Statistically Different" from one another. My dataset is comprised of groundwater laboratory results from a stream, one upstream and one downstream. There are 54 individual parameters that comprise my entire dataset. I will be comparing each parameter...
  2. J

    paired sample t-test vs. repeated measures ANOVA

    I think that the Psychology Research forum is more appropriate so I moved my question there--I could not figure out how to delete this thread. Thank you for having a look!
  3. J

    Overlapping sample: t test with partial pairing??

    Hi - I've a work project that requires a stat test between Product A and Produce B performance ratings (On a scale of 1 to 5 how well did Product A / B perform?) We are treating the data as interval scaled. The samples partially overlap. e.g. Product A has n=500; Product B has n=500...
  4. P

    Permanova + T-test

    Hello, I have a question regarding the data analysis listed below. I am trying to run a similar study but I can't truly understand why a PERMANOVA was used. Any help would be greatly appreciated. In my study, I am comparing prey species composition, abundance, pecking rate, and swimming...
  5. R

    Interpreting Independent Sample t-Test results

    Hello folks! I'm having a hard time understanding the output that SPSS gave me regarding my Independent Samples t-Test. Can anyone help me describe this output? I've attached the output for you.
  6. O

    Change scores: t-test or mann-whitney U test ?

    Hi there Nice forum btw. Question: I have change-scores on pain in 37 patients pre/post intervention. which test do you use? t-test or mann-whitney U test? i was told that with change-scores they are always normally distributed and i can use a t-test... any reference for such a...
  7. R

    comparing and accounting for temperature difference between two locations

    Hi, I'm a student currently undertaking my dissertation. The aim of my research is to try to gain an understanding of what informs people's temperature perceptions, with a specific focus on cultural theory, although other sociodemographic questions were also asked in the survey. One of the...
  8. H

    Help with the normal distribution using R

    Hi! We are total statistics and R-newbies, and we're having some difficulties with our data that we hope some of you might be able to help us with. The problem is that we don't know how to check if our data is normally distributed/we don't know how to make it look normally distributed...
  9. M

    paired sample t-test for repeated measures in 1 subject

    I am conducting a psychology experiment. In my pilot study I analyze responses of one subject which ran through two conditions. The task is to predict outcomes based on previous outcomes. On every trial the subject tries to predict the outcome as good as possible and learns to adapt the...
  10. S

    Rsearch Design

    Hi, I am currently writing my dissertation. My lecturer told me my research design is repeated measure with multiple groups, however she is currently off on sick leave and have been told other lecturers can not help me. I am questioning her choice (unwisely probably), as I can not seem to...
  11. L

    Z-test? Paired t-test? T-test two sample assuming equal variances?

    Hey guys! I'm hoping this is the correct forum to post this in. I'm working on my senior thesis, and it's been a while since I've taken stats so I'm hoping you guys can help out. I'm looking at firms following an event and finding the return on their stock price in a set time period. I'm...
  12. B

    T-Test Help

    Hi I am totally new to stats and finding it very difficult. I was wondering whether or not anyone could help me understand which T-Test to use to try to see if my results are statistically significant. I'll try to explain the situation. I have 8 sub groups, which make up two main groups (A...
  13. H

    Which Statistical Test to Use?

    I am doing a research project in which I have collected variables on two separate groups. One group uses a self testing laboratory machine which I have labeled as "patient self testers" (PST). The other group does not use the self testing machine, "non-patient self testers" (non-PST). The intent...
  14. S

    Need help with medical study

    Hi, I'm writing a medical paper on asthma and I'm afraid I 've reached a point where I am unconfident of my statistics knowledge. I am hypothesizing that there is a relationship between elevated concentrations of a substance in the blood (we will call it X) and severity of asthma...
  15. M

    T- Test output

    Hi, I am conducting an independent T-Test in SPSS (users and non users) against a range of independent variables. I now have found significance in one of my variables (perceived compatibility) the results are; t(49) = -3.357, p=.002. Am I right in thinking that because my t value is negative...
  16. A

    One-way anova or paired t-test on intervention study? OR BOTH?

    Hi all. I'm planning a study where I get 3 separate groups of people, make them all do a satisfaction questionnaire, then give each group one different intervention (i.e. 3 different interventions total) and then get everyone to do the same satisfaction questionnaire again after the...
  17. R

    How to calculate p-value of two-sample t-test

    I have 2 independent data sets, and I know the following about each of them: mean, SD, and sample size. I calculated the t-statistic just fine my.t.test<-function(mu1, mu2, sd1, sd2, n1,n2){ t=(mu1-mu2)/sqrt((sd1)^2/n1+(sd2)^2/n2) return(t) } I know that the degrees of freedom...
  18. I

    Confusion over t-test and anova?

    I'm having trouble with the statistical method in which to assess my results. I have a line graph that i have plotted mean values of cell survival (Y axis) against concentration of a drug (x axis). The concentrations are 0, 1, 3, 10, 30, 100 and 300 uM. I have also plotted the standard...
  19. P

    Likert type data and testing group differences

    Hello, I have a Likert scale (5 points) with 37 items. And I have some independent variables such as gender and age (4 categories). I want to test differences between gender and age for all of the items. For example I want to test if there is significance difference between girls and boys...
  20. C

    t-test or f-test

    Hi all, Apologies for the nature of my post but I'm a relative beginner to statistical tests. What I would like to know, is if I have two sets of data (as I'm a microbiologist, the data sets are likely to be bacterial colony size measurements on two different agar plate types), why would I...