A proportion is the fraction of some total that is of a particular kind, either (i) as a count of one type of thing out of a total count, or (ii) as a component of a continuous variable.

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Proportion Sample Size Estimation? Cluster Sampling

I was asked by someone running a food drive to help with the following problem: Food is being collected in bins, which hold about 1,500 lbs of food each. They are looking to collect about 500-600 ...
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7 views

Interpreting negative regression intercept; proportion response to categorical predictors

probably a simple answer and I'm overthinking or something. I have regression output (Zero and One Beta regression with GAMLSS). I'm analyzing the proportion of time spent demonstrating a certain ...
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2answers
39 views

Why is confidence width narrower, when sample proportions are smaller?

I am using a binomial distribution to calculate confidence intervals around a proportion. I noticed that for a fixed sample size, the width between the confidence intervals gets narrower as the ...
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18 views

Difference in differences in proportions statistical test

I am running a case-control interventional study where the dependent variable/ outcome is a proportion. The cases were given an intervention whereas the controls were not and measurements were taken ...
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11 views

Calculating SE for set of proportions with different sample sizes

Okay, so I have a data set where I'm measuring survival rates under different conditions. I have three treatments, control, pH 1, and pH 2. Each one has six replicates, all of which have different ...
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1answer
48 views

Understanding default Bayesian posterior probability shape parameters in multi-armed bandit

Multi-Armed Bandit indicates a best "arm" based on a simple test of proportions and Bayesian posterior probability shape parameters, alpha and beta (some implementations may take a different approach, ...
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19 views

GLM model specification in distribution and link function for fractional (percentage) response data

I have some aggregated data. Indep. Dep. N 1.3 78% 23 1.2 67% 20 Note that both the independent and dependent variables are aggregated by ...
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8 views

Survey sample size

I am trying to learn something about survey design and analyisis and I have a doubt about the number of people that should answer a multipurpose survey in order to estimate several proportions. If a ...
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1answer
26 views

How to model percentage dependent variable using logistic regression in spss

I have some aggregated data. Indep. Dep. N 1.3 78% 23 1.2 67% 20 Indep var the average score of people in a particular region. Dep. var ...
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10 views

Two different sample sizes, testing accuracy

currently working on my dissertation for my final year project and have come across a problem. I am not a statistician or a mathematician so excuse me if the question is very simple to solve, can't ...
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1answer
22 views

Why does my power vary markedly between a z-test (2 proportions) and a chi-squared test?

I have two groups, with 100 people in one group(1) and 80 people in the other group(2). 42% of group 1 love cake. I am wondering what proportion of the 80 group 2 members would need to love cake for ...
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30 views

How can I account for range restriction when meta-analytically aggregating differences based upon bounded measures such as mean proportions?

Background and Problem In the past, I have read or conducted meta-analyses that aggregate effects based upon mean proportions. For example, in a typical psychological experiment dealing with human ...
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21 views

Sample size to test small proportion

What sample size $n$ is required to test the following binomial probability in a single sample: $H_0: p \leq p_0$ $H_1: p > p_0$ Is there an exact, robust formula to calculate $n$ in terms of ...
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1answer
21 views

Testing statistical significance of three percentages with ANOVA?

I want to compare the mortality rates of three groups. Can I use ANOVA? If so, how will I deal with the percentages?
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1answer
20 views

Comparing a distribution of percentages

I have two populations that I would like to compare, each of which contains N samples. Each sample itself contains many events that can be categorized into 20 different, mutually exclusive, ...
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2answers
31 views

Can I estimate the optimal proportions of ingredients in a blend?

I'm trying to find the optimal blend of 4 ingredients, to maximize liking of a beverage. I can write a function for liking such as: Liking is on a scale of 0 - 1 (0% - 100%). I conducted 10 ...
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13 views

GLM on Proportion Response and Categorical Predictor gives strange standard errors

I am looking at the effects of seawater salinity levels on fertilization rates. Salinity levels are set so they are treated as factors. ...
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11 views

Chi post-hoc OR Z cell comparisons: do 2 proportion z-tests indicate most significant factors?

Attached is an example of some data I'm working with. I'm testing the occurrence of a rare behavior, while controlling for both education and the "bin" variable. The observed sample size is 129. This ...
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6 views

Calculate confidence interval of proportion for cluster sample which none of the subject has the outcome of interest

Let say that I have collected response from 100 subjects using cluster sampling, and none of them has the outcome of interests (e.g. having lung cancer). For simple random sample, I can still ...
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14 views

Appropriate Correction for 2 proportion test? --with example--

Below is an example of frequency data between observed and expected proportions. Can I simply run a 2-Proportion z test here? Or, would I be violating assumptions? If I were to run dozens of z tests ...
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10 views

Mixed effect models and data that has floor effects (and is proportions)(sort of)

I've been asked to analyze some data using linear mixed effect models (via lmer in R). However, I'm not sure this is the appropriate approach to the data. I am going to provide some background detail ...
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14 views

Confidence Intervals for population proportion where the sample proportion = 0 [duplicate]

Does the lower bound of a confidence interval for a population proportion where the sample proportion = 0 (and the sample size is finite) contain 0? If I use the score-based method, it seems to me ...
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4 views

Finding proportion of variability from a model?

With proportion of variability explained by each variable in the model, how do we handle a value that is a negative (-) number? thank you!
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12 views

How do I determine proportional variance between 2 sets

How can I determine whether the proportion of variance for each ID between rating is in proportion to the Allotment? for example in this dataset, rating has a range of 25 while the allotment has a ...
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1answer
54 views

Fitting a truncated normal distribution between 0 and 1 with a logit link function in R

I am modeling data that are proportions between 0 and 1, with many values of 0 and 1 in the data set. I'd like to model this as a truncated normal between 0-1, using a logit link in ...
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26 views

Regularized Generalized Linear Models with an incidence as response in R

I'm struggling to find a regularized regression model with a percentage as response variable. I've already seen the glmnet package in R and it seems that there is not way to handle a proportion as ...
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7 views

Confidence interval of a proportion [duplicate]

My objective is to estimate the proportion of A and B in a mixture of A+B. I use a classification method (SVM) which provides classical "error" metrics for classification (percentage of good ...
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16 views

Test equality of multiple proportions

Conciser a cross-tab like this (or equivalent just with different number of either classes or folds): ...
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1answer
34 views

Dealing with 0 in cell count for Fisher's exact test

Control Cases A 0 2 B 1000 298 I am dealing with 0 in my 2x2 tables, and I was wondering what are some of my options when it comes to ...
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9 views

comparing proportions in multiple age groups

The hypothesis is that with increasing age the occurrence of ovulation is more frequent. I have binary data (ovulation / no ovulation) for four age categories in cats, some of the individuals may show ...
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4 views

Sample size to compare 2 treatments

Situation here to compare binary outcome between 2 treatment groups BUT the problem is that each treatment will be given for either of 2 durations (short or long) based on early response So we ...
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1answer
94 views

What is the most appropriate way to transform proportions when they are an independent variable?

I thought I understood this issue, but now I'm not as sure and I'd like to check with others before I proceed. I have two variables, X and ...
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1answer
57 views

chi squared with proportions

We want to know whether there are any differences in the location of mole hills that occur in two fields. We have been looking at the distance from a fence that mole hills occur. We have separated ...
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2answers
77 views

Beta as distribution of proportions (or as continous Binomial)

Beta distribution is related to binomial being also the distribution for order statistics. Probability mass function of binomial distribution is $$ f(k) = {n \choose k} p^k (1-p) ^{n-k} \tag{1} $$ ...
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27 views

How to conduct a Generalized LM in SPSS, with proportion dependent variable

I must deliver some analysis result report, by using a Generalized Linear Model for a dependent variable I have, which is in proportion values (invisibility), with two factors. The first factor is a ...
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1answer
31 views

Machine Learning Procedure for Fractional/Proportional Data?

I am looking for some suggestions of machine learning procedures that work to predict fraction outcomes where the outcome variables $\in [0,1]$. Can you provide me with any suggestions? I thought ...
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1answer
27 views

Why do we transform proportions and what are the methods to do that?

When proportions are condensed below 1%. It become asymmetric on the distribution curve, so we get the log() of the proportions to make it symmetric around zero. Is that correct what else can the ...
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34 views

test statistic for change in proportion over time?

Stats novice here. This is my problem: I have 7 samples corresponding to the years 2006-2012, representing emergency department [ED] visits. For each ED visit, X=1 if the visit had diagnostic ...
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32 views

Probit Model: Interpretation of marginal effects if explanatory variables are proportions

How do I interpret the marginal effect of an explanatory variable that is a proportion in a probit model? For example if I get a marginal effect of 0.8 does this mean that if the proportion increases ...
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33 views

Cochran-Mantel-Haenszel test for before after data? Or something else?

I'm trying to assess proportional vegetation area change over time. I would like to test whether the area of trees has decreased significantly within different areas between two time periods ...
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1answer
29 views

Test of proportions - proportion with CI versus given value

I am working on one clinical trial, where the primary goal is to compare proportion of overall survival (OS prop) after 12 months between our study and other registration study. I computed the OS prop ...
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22 views

standard error for difference in proportions between a population and a subset

I have a reference population and a non-random subset of that population. I am interested in the difference in proportions between the subset and the population. If my subset were a random sample of ...
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1answer
54 views

What does this mean “the standard deviation of a proportion is a function of the proportion itself”?

I was studying calculating power and sample sizes and i came across this paragraph: Calculating Power for comparing two proportions has the same idea as with comparing means, except that no ...
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81 views

Using poisson distribution to model proportions

I have recently came across a number of articles that have used Poisson GLMs when modelling proportion data. For instance, one study modelled the proportion of pig mortality for each sow using a ...
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19 views

Summary statistics for mean of proportions

I have data from 30 subjects, each subject performing 50 trials and making a binary choice (category A or category B). I want to know if overall the preference is for category A or category B. I ...
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1answer
85 views

fitting a binomial glmer or an lmer to a proportional response variable

I'm hoping somebody can help with what I think is a relatively simple question, and I think I know the answer but without confirmation it has become something I just can't be certain of. I have some ...
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1answer
93 views

Comparing p-values for Fisher's exact test and test of equal proportions

I'm comparing success rates for two repeated experiments with $n_1$ and $n_2$ successes out of $N$ trials. $N$ is in the order of $10^7$. I don't know beforehand which experiment has a lower success ...
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22 views

Second type error for difference in proportions test

I want to calculate the second type error Beta for a difference in proportions test, in a two populations scenario. Google search guides me to different tutorials to perform the test of proportions, ...
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38 views

How to calculate standard error for WEIGHTED count data aka proportions

First let me explain my data. I have 30 residential subdivisions. Within each subdivision, I randomly generated n=50 points over an aerial photograph. For each subdivision, I counted how many points ...
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14 views

Comparing proportions between 10 groups

For an experiment, I have a large dataset of tweets from 10 different subjects. The dataset contains around 300 tweets per subject. I'd like to find out whether the subjects differ from each other in ...