power

  1. C

    Bonacich Power

    I am working on some network statistics, and used Bonacich Power as one of my centrality measures. I understand that by choosing the beta parameter < 0, would mean that nodes connected to nodes that are less well connected would have higher power. I have two questions (1) How would one interpret...
  2. R

    Is there a way to increase power in my study

    Hi everyone, I'm working on my 'behavioral change' master thesis. My goal is to design an intervention to reduce printing at the workplace in a big organisation. Unfortunaltely i dont get provided with the printing details on a personal level, so my best bet is too see how much a printer...
  3. B

    Post-hoc power analysis for a Welch ANOVA and also a Kruskal-Wallis test.

    I planned to analyse some data with several ANOVAs (I have many different dependent variables), but much of the data violates the ANOVA assumptions, so they require Welch's ANOVA or the non-parametric Kruskal-Wallis test instead. Using SPSS, I generated effect sizes (partial eta squared) and...
  4. hlsmith

    Sample Size Calc for Right Skewed Data

    I have a request from a person for a sample size calculation. When I requested information about the potential study data they provided two means and standard deviations from a prior study. Given the values (x1=7; s1=6 and x2=0.5; s2 = 2) it appears the data are right skewed. I can simulate...
  5. Junes

    Power calculation with measurement error on Y

    I'm trying to do a power calculation for a study I'm involved in, and I'm a bit stuck. The study is about textual cues of trust. We want to analyze a number of predictors in the text using the LIWC tool (which generates features based on text) and correlate them with perceived trust as...
  6. P

    ANOVA on simple proportional accuracy scores versus on d prime indexes

    To answer this, you would need to know what d prime is. Here is a link: http://www-psych.stanford.edu/~lera/psych115s/notes/signal/ The method I used is z-score "hits minus false alarms" When I run an ANOVA on simple proportional accuracy scores I find no interaction between condition A...
  7. I

    Power calculation

    Conducted a preliminary study & want to determine if i need more participants. How do I do this using spss 30 n , 10 stimuli (2 subcategories, 5 cats, 5 dogs). 7 point scale (not at all - very much). Used % as marker of neutral scores.
  8. M

    Help with statistical power?

    Hi, I'm doing a study looking at the ability of a test to detect a change in bacterial numbers pre- versus post-treatment [i.e. not treatment effect, but pilot study looking at efficacy of the test used]. I've done a chi-square test and got a significant result (p<0.05). However given that I...
  9. S

    Best way to calculate power, precision & sample size using complex pilot data set?

    I have a large and complex pilot data set of electromyographic (EMG) data collected from human subjects performing several different exercises. A single subject was used for all data collection in this pilot experiment. Each data set involves one particular exercise being performed with one...
  10. C

    Does Imposing a Constrain Make a Method More Powerful?

    Suppose we have 100 patients in a randomized trial. 50 of them are in treatment group and the rest are in placebo group. This is a longitudinal study so that we measure the response from each individual at four different periods: baseline, week 1, week 4, and week 6. Now suppose we have good...
  11. S

    Calculation population size and analysis of a study comparing two outcomes

    Calculation sample size and analysis of a study comparing two outcomes Hi i'm having difficulty finding an answer to this specific problem. I'm preparing a pilot study comparing two medical devices. Each device reads a patient's physiological / laboratory data and provides a...
  12. M

    Comparing the Power and Effect Size from Different Studies

    Hi there Talk Stats Community, I am an undergraduate research assistant. Currently I am doing research on a project, and our results have indicated something that is quite different from previous findings. We have used a more specific and sensitive test to prove that a particular microbe...
  13. N

    Power analysis (gpower) - interactions

    I'd like to conduct a power analysis in gpower to determine the total N required in a study, with the following requirements: power desired: 0.80 alpha: .05 effect size: unsure what to use here (explained below) study design: 2x2 within subjects anova (4 conditions) where my main...
  14. K

    sample size calculation for paired proportions when one discordant pair is 0

    Hello! I am trying to calculate sample size for a study using paired data. My groups are such that one discordant pair will always be 0. I planned to use McNemar to test for a difference between the groups, however, I am not sure this is valid since one discordant pair will always be zero...
  15. S

    Bayesian AB Testing - Minimum Sample Size

    I've used python to analyse data from AB tests using Bayesian analysis, and for all tests I assume no prior knowledge and so set alpha = beta = 1. However I'm finding some odd results at low data volumes, which I thought was my code, but I'm also seeing here...
  16. O

    Confusing Power of T Test!

    Hey all, This is my first post to this site. My question is: I am using this (given) regression to find the relationship between gender and wage: Lnwage = Beta0 + Beta1male + Beta2Professional + Beta3Management + Beta4Educ + u My professor wants me to test the power of the test with...
  17. J

    Power test - which one is suitable for me

    I have a group of 200 female individuals that are either infected or uninfected. The infected proportion is known at generation (G) 0 when I mixed infected and uninfected females at 10% (therefore 20 infected, 180 uninfected). This infection frequency is expected to increase in each...
  18. M

    When do sample size calculations need to adjust for clustering?

    I am aware that sample size calculations for cluster RCTs must adjust for clustered data. I would like to understand better if such adjustment might be necessary for other study designs. For instance, I am working on a nested case-control study to identify clinical and socio-demographic factors...
  19. Y

    [JMP] Does any body can explain me on one sample size what formula used in JMP?

    Hi, sir. As below table, I have so many items to do analysis with One, Two, K sample mean. Is there any jmp formula in "Sample size N" same as jmp under DOE "Sample size and power" Please help me. Item Sigma σ Delta δ Sample size N Method A 1.0088...
  20. T

    PowerAndSampleSize.com

    So I'm starting a website (see thread title) devoted to statistical power analysis and sample size determination. Why? B/c I make power/sample size calculations all the time in my work. Sometimes a common statistical test will do; sometimes something a little more complex. But, invariably...