sample size calculation

  1. P

    Calculating sample size based on incidence rate?

    I would like to calculate the necessary sample size for a retrospective cohort analysis. I will be comparing male with female and my outcome will be extra-articular manifestations (EAMs) in patients with spondyloarthritis (more specifically, axial spondyloarthritis and psoriatic arthritis)...
  2. G

    Simple Sample Size Calcs

    Hi all, I am looking into the feasibility of mailing (post) churned customers with various long regencies. I want to get an idea of their likely response rates by recency with a small test prior to rolling out to some or all of these regency’s. Using online calculators or the formula behind...
  3. E

    Psychometric sample size requirements

    Good afternoon, What is the guidance for psychometric sample size requirements? For instance, say I developed a psychometric tool to assess resilience with scores ranging from 0 to 100. Let’s say, the Los Angeles County Unified School District has agreed to use my tool to assess resilience...
  4. H

    Sample size calculation

    Dear all, I am going to be carrying out a study, however, there is insufficient data to inform us of some information to calculate the sample size. Would be best to use effect size to calculate the sample size then? Thank you in advance,
  5. K

    Sample Size Calculation with RPV

    Can you calculate a sample size using revenue per visit (RPV)? If so, are there any online calculators, Excel formulas or tools that can be used for this? I have tools for calculating significance with revenue, but have not seen anything for sample size. Thank you!
  6. A

    Can you use finite population corrector in getting the sample size of an analytic study?

    Our research is about burnout and its associated factors. In computing for the sample size, we used open epi calculator, the one for cross-sectional study design. (We computed for each factor we wanted to associate and looked for the highest sample size.) We obtained a very big sample size...
  7. A

    Sample Size calculation - "difference in mean differences"

    We have two independent patient groups in an Individual RCT ("treatment" and control["standard care"]). The treatments will result in a change of scores on a psychometric scale, from baseline to end-line. A baseline assessment was conducted using this scale, and thereafter, the participants were...
  8. C

    Sample size estimation for evaluation of diagnostic tests

    I am studying 2 blood tests (A and B) to detect infection following exploratory laparotomy undertaken to treat various surgical lesions. In other words, the population is somewhat heterogenous. In a similar previous study (51 patients), other authors reported on test A. The blood will be sampled...
  9. E

    Sample size, effect size and power.

    Hi all, I have a question I haven't been able to answer. I hope you can help me :). I use G power to estimate sample size. In my case, the estimated sample size for my desired effect size = 0.25 and power = 0,95, is 400. But the estimated sample size for an effect size = 0.5 and power = 0,95...
  10. P

    Sample size for observational study

    Hi everyone! I should to calculate sample size for observational study in that the primary endpoint is to assess the distribution of COPD by 4 classess (COLD). According to article i know expected distribution by class: 1 class: 16% 2 class: 25% 3 class: 28% 4 class: 31% How I may to estimate...
  11. J

    Sample Size for Variable Data

    Hello, I am trying to determine whether or not our sample size criteria is correct. Some time in the past, my company adopted a standard practice document that lines out sample sizes based on certain criteria, i.e. variable vs. attribute, critical to quality vs. non, software, etc. My question...
  12. S

    Sample size calculation for cohort study

    How to calculate sample size for cohort feasibility study? I use the online tool: http://clincalc.com/Stats/SampleSize.aspx Any other options available? Please suggest.
  13. T

    Adequate subsample size to represent sample regression

    I am performing an engineering analysis to find out the effect of earthquake on concrete buildings. Analysis applies earthquake forces on building model for 50 earthquakes, resulting into separate 50 analyses. Earthquake intensity is independent variable of study. building drift, extracted from...
  14. S

    Design help

    Design help
  15. R

    AB Test with Proportions

    I'm trying to design an AB test for proportions, and I need to understand the minimum sample size I need to get a statistically significant result within a 5-10% change of a very small proportion. This calculator summarizes the type of test I'm trying to set up: https://abtestguide.com/calc/...
  16. E

    Engineering Research, starting to look at statistics

    Hey everyone, This will be my first post on this forum. I'm an engineering grad student and I have a little experience with statistics,but not enough to be able to do a sound analysis. I've completed my system design and will start looking at data collection. My primary aim is looking at...
  17. D

    Sample size calculation

    I have a normal distribution: log(xi/yi) ~N (0, c^2/yi). I need to work on the posterior distribution of c^2. I know c^2 follows a gamma distribution. I need to know what sample size I need to estimate the c^2?
  18. S

    Determining sample size from confidence interval and significance level

    Hi everyone, I am studying a university level stats course at the moment and I have been given some excerises to take home that I am struggling with. I am asked to calculate sample size for a hypothesis that requires an 90% probability of detecting a difference at a significance threshold of...
  19. B

    Sample size in a lot with clumped error

    Hi, A big bag is emptied in X amount of smaller bags. We are trying to detect an error which is clumped. In other words, if an error is detected into 1 of the X we are sure all the other small bags with errors are grouped around that initial sample. Is a sample size described in the following...
  20. C

    Sample Size Calculator (one group versus population)

    Dear all, so far I couldn´t find a solution to calculate the required sample size for the following scenario: Goal: Research continuous variables (cost perceptions) of a population through one sample group. --> means of one group need to be significant for the entire population...