t-test

  1. O

    T Test

    Hi T-Test is used instead of Z-Test when we don't know the standard deviation, or when the sample size is too small (less than 31) When we know the standard deviation but the sample size is small, do we use T-Test with sample standard deviation (S)? or T-Test with the known standard deviation...
  2. I

    How would you enter this data?

    I have to do a t-test (it doesn't say which type of t-test) in SPSS about the olfactory scores of smokers and non-smokers. For smokers, we are given the scores so I know how to enter that in SPSS. For non-smokers, we are not given the scores, it simply says “On a test of olfactory sensitivity...
  3. D

    Which test should I use?

    Hey everyone, I would like to determine if there is a difference between two sets of data. The data is from two separate treatment groups on yeast, and we have ran each experiment lots of times and have created a normal distribution for each set of data. If I want to test for a statistical...
  4. S

    Dependent Samples T-test - different formulas?

    I have a question regarding hypothesis testing when the samples are not independent. The formula I know for the test statistic for a paired samples t test is where you divide the mean difference by the standard error. I've come across another formula that instead subtracts the mean 'after'...
  5. J

    Can someone please confirm if I have selected the right tests for hypothesis testing?

    Hi, this is my first post here, hope that I'm doing this correctly! I'm taking a statistics course for my master's where we need to do some hypothesis testing with a pre-defined data set using R. I am unsure about what the most appropriate statistical test to use is, so I was wondering if...
  6. T

    One or two tailed test?

    Hi, I am currently struggling to decide whether the following problem requires a one or two tailed t test for a hypothesis test. I have uploaded a photo of the data used if needed. 'Test the individual significance of the explanatory variable. You should decide on an appropriate t-test (one...
  7. B

    Help please - what tests do I need to do?

    Hi, I'm struggling to figure out which tests I need to do for my project. I have two things I need to do. 1) I need to know whether males and females varied on a continuous outcome (how strongly the believed a witness was credible in a trial). How would I do that? 2) what analysis...
  8. A

    Chi Square or T Tests for Likert Scale Type Survey

    So I have a 4 point likert-type scale with approximately 20 questions. I have categorized each item to be either agree or disagree. I mainly did this because the previous person who used this scale did this. However, that person only displayed frequency data for it and did not run any tests for...
  9. T

    Question about degrees of freedom in an independent sample t-test

    I've been asked the following question by a scientist who is not a statistician: Suppose we take a sample $x_1,…,x_n$ from a population that we can assume is normal (I don't think this assumption is critical). We then calculate the sample mean $\bar x¯$ and variance $s^2$. We then take a...
  10. W

    comparing test results obtained on the basis of different sample sizes

    I have variables a1 and a2 with 57 observations each, and variables b1 and b2 with 29 observations each. I compare a1 with a2 by means of a paired-samples t-test, this gives p<0.001. Next, I compare b1 with b2 by means of a paired-samples t-test, this gives p>0.05 (actually p>0.10). I compared...
  11. F

    I need some help for my thesis about t-testing different data sets

    Hello everybody, I'm conducting research on price dispersion to show that offline price dispersion is significantly smaller than online price disperison. I have up until today, monitored and collected over 1500 prices in excel on several homogeneous products in...
  12. C

    Assumptions for comparing means and which test to use

    I am attempting to compare the means of soil moisture measured from two adjacent soil profiles at both 10cm and 30cm. Soil measurements were measured discretely six times over the course of two months at the same date and time for each profile. However, when looking to perform tests to compare...
  13. C

    What test do I use?

    I have done a study comparing double leg and single leg landing techniques, I want to look at the differences between knee flexion, angular vel, and GRF between the two conditions, what test should I use? I would appreciate any help at all!
  14. M

    Can I use an independent t-test to test for significant differences over time?

    I have a 50 year time series (2012-2062), and I would like to test to see whether sig. differences exist between two groups of data subjected to different conditions. I understand that a t-test tests for sample means, however does this test still apply if I am looking at differences over time...
  15. S

    Selecting of statistical test?

    I have a study whereby I asked two groups of participants (Clients (N=76) and Professionals (N=62) what qualities would make a treatment interaction positive and what qualities would make a treatment interaction negative. As part of my analysis I have totalled: - the number of positive...
  16. T

    ANOVA or T-test

    Hi I have two categorical variables as in below example: Region Dim Value PK Dim1 2 PK Dim2 3 PK Dim3 -1 PK Dim4 -4 US Dim1 -0.5 US Dim2 4.3 US Dim3 2.1 US Dim4 2 PK Dim1 5 PK Dim2 -0.4 PK Dim3 -0.3 PK Dim4 0.8 US Dim1 1 US Dim2 2 US Dim3 0.8 US Dim4 1 I want to compare the variables US and PK...
  17. P

    Which statistical tests are appropriate: Group means before and after treatment

    I am trying to find out what statistical tests to run on a set of aggregate data (no individual data) on 3 different groups, variables are summarized below: Group 1 in site 1: Mean value (blood sugar) of the total sample before treatment, and mean value (blood sugar) of the same group after...
  18. E

    [SPSS - T-Test] - understanding how to approach a question

    Hello, I have I inputted my data into SPSS. This is the question that I have been given: Compare the QABF attention(interval data)scores and demand(interval data) scores of people with a diagnosis of FXS and those with any diagnosis. Are people with FXS more likely to have lower...
  19. M

    ANOVA or t-test?

    I want to test 2 different treatments (diets), repeating each treatment 3 times on 25 individuals independent samples. After each repetition, four variables are measured on the individuals (weight, size, variable3, variable4) all quantitative. I want to assess the differences between the...
  20. J

    What would be the appropriate statistical tool?

    Dear all, I am a graduate researcher in the analysis phase of my research work. My research is an intervention research (n=14) trying to analyze the impact (pre and post) of the sports program. I don’t have a control group for this research. My dependent variables fall under ordinal, likert and...