power

Hi, I have a power calculation question. I have an initial study that has 6 subjects (all treatment group) and a follow-up study with 60 subjects (randomized into treatment and placebo 1:1). Can I find the probability of any of the 60 subjects experiencing an Adverse event, if >=33% of the...

For statistical modelling and datamining, we have an assignment where we have to create a good exam question. I managed to come up with this. Would you consider it a good exam question or do you think it misses the point? ++ 1 What measure for classification and diagnostic testing should be...

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...

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...

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...

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...

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...

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...

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.

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...