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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Expected survival time: comparisons when measurements are an average over other measurements?

Set up We have a few types of interventions. For each intervention, a failure occurs randomly at some time $t$ after start for each subject. We take $n$ measurements of $t$ using $n$ subjects, and ...
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16 views

Zero-heavy dataset with proportional independant variable

I am examining the effect of a binary variable (rural vs urban) on my dependant variable (total mileage expense). Essentially, a person (n) will do X amount of trips in one year, and Y trips will be ...
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25 views

Pitfalls of using random forest/GBM on proportion data?

I have a set of data with a dependent variable which represents a proportion, and many of the samples contain a response of 1. I would like to build a random forest or GBM regression model on the ...
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39 views

two samples, hypothesis test of proportions t or z test

I have two samples of documents where one sample contains documents of a certain category and another sample contains documents of another category. I am analysing the occurrence of a certain word in ...
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20 views

Compare proportions more than two groups

I have a survey where teachers are responding "yes" or "no" to lists of activities that they did in their classroom. There are separate checklists related to separate parts of the curriculum (e.g., ...
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1answer
77 views

Confidence interval for the ratio of two related proportions (glass ceiling index)

I would like to compute the confidence interval of the glass ceiling index (GCI), which aims to measure gender inequality in Academia. According to "She Figures", the GCI is defined as follow: The ...
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1answer
31 views

When to report proportions and when to report median + IQR for ordinal variable

A colleague brought to my attention documentation for a standardised questionnaire which recommended using the median and interquartile range to describe summary variables created by combining ...
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4 views

How to compare series of foreclosure rates wrt to time and place

I have three categories of foreclosure rates in NYC (rates are number of foreclosures per 1000 homes). The three categories are: overall rates of foreclosure, rates for homes within a flood zone, and ...
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10 views

histograms/ kernel density estimation for proportion data

I am looking at digital advertising data with the following columns: site_id | impressions_count| clicks_count. I am interested in a histogram of the click through rate (clicks/impressions) across ...
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How to analyze data with restricted range proportions

I have a dataset where one variable is a proportion with a restricted range (say 4%). I would like to use this variable to predict a death rate. Running a simple correlation I'm guessing would ...
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54 views

Posterior distribution of proportional difference of two binomial variables

Can somebody point me in the right direction for a treatment of the following problem? I imagine this should be a fairly common problem in medical statistics... Given two binomial random variables ...
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1answer
22 views

How can I do a test for proportions when the data has been collected weekly from the same general population?

So I have a series of proportions taken weekly for 7 weeks. This is a study of which way spiders were facing. So for example, the first week, 20 spiders were facing out, and 10 were facing in. Now I ...
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26 views

How to structure data for SPSS (percentages for log-linear analysis)?

I am a bit desperate because I am writing my Msc thesis and I am not sure how to organize my data for an SPSS usage. My research examines the performance of mobile banner campaigns and how the 3 ...
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1answer
37 views

AB testing vs testing the null hypothesis

I'm trying to understand the difference between testing the null hypothesis (i.e. testing that the probability of a "goal" is the same across 2 different populations, similar to prop.test in R) an ...
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9 views

proportions at two times with predictor

I wonder if anyone can help me. My data has 3 main variables: proportions at 2 time periods, and an additional predictor. For example: Item Type Y(t) X Y(t+1) 1 .05 ...
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25 views

normalizing a proportion of poll results given unequal gender response rates

I took a poll of patients who experienced at least one misdiagnosis. I'd like to analyze the data according to gender but 75% of the responses came from Females and 25% from Males. Example: The data ...
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1answer
30 views

Assessing whether differences between datasets are significant

I am unsure which statistical test I should use to test whether two datasets are significantly different. The data looks something like this: ...
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1answer
15 views

What is the best way to quantify concordance of two tests?

I have two different medical diagnostic tests, both test the same condition (binary outcome). The condition in question is rather vaguely defined, so they don't always agree. What would be the best ...
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1answer
43 views

Which regression analysis should I use for ranked dependent variables and proportional independent variables?

I am analysing the effect of deprivation on breastfeeding and am wondering which type of regression analysis I should use. It is area level data. Deprivation data is available as a score from 0 - ...
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28 views

Best proportions test based on counts (accuracy, distribution, etc)

I'm trying to compare two sets of counts over totals. For example, subject 1A will have 40 out of 600, and subject 1B will have 3 out of 20. How do I compare these proportions and counts while taking ...
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1answer
91 views

Empirical logit transformation on percentage data

I have already used the logit transform on my outcome variables (which are displayed in percentages). However, this obviously gives me -INF values and since my data includes a lot of zeros in some ...
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39 views

Is a sample of 1961 people out of a population of 225,000,000 a sample size that is too small? If so, why?

I am working by a set of problems on a single question in my textbook. The question explained that there was a recent survey of 1961 adults out of a population of 225,000,000 and asked me to construct ...
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1answer
36 views

Taking a random factor into account while measuring a proportion a low N

I need to be neat in measuring the success rate of a treatment. It is anyway pretty high. But as it is all about ecology, multpliying experiments is difficult. I have treated $N = 20$ individuals, ...
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1answer
28 views

Transforming data for canonical correlation analysis

Okay, I'm a stats newbie so I'll try to be as specific and clear as possible. I have a set of predictor variables (2 predictor variables) and a set of response variables (7 response variables). I am ...
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1answer
49 views

wilson's adjustment for sample proportion

Could somebody provide a derivation for Wilson's adjustment for the CI of a sample proportion? The formula is: $$\tilde{p} \approx \frac{x+2}{n+4}$$ where $x$ is the number of successes, and $n$ is ...
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72 views

Seeking a continuous, parametric, bimodal sampling distribution for proportions

I am seeking a parametric probability model whose pdf has the following characteristics: (1) it is supported on a variate axis that is bounded between 0 and 1; (2) it is continuous; and (3) it is ...
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139 views

Is it possible to statistically test relationships between counts and percentages?

I have counted adult butterfly numbers over 3 areas and would like to compare these counts with the percentage heather cover on each of the 3 areas. Is this possible? My data looks like this (the ...
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1answer
22 views

Comparing percentages from one sample and between samples

I've conducted a large survey with about 600 responders. Most of the questions were multiple choice questions. I'm interested in comparing several kinds of percentages. First, I'm simply interested ...
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16 views

Test for relative proportions

This is my first question here. I have experimental results for two datasets where I want to check if the difference is significant or not. Here is a description of my experiment: Experiment: I have ...
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1answer
166 views

R - power.prop.test, prop.test, and unequal sample sizes in A/B tests

Say I want to know what sample size I need for an experiment in which I'm seeking to determine whether or not the difference in two proportions of success is statistically significant. Here is my ...
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1answer
20 views

Testing change in categories?

I hope that someone will be willing to help me with the following question. I have data on the numbers of hours participants spent in 6 programs over 2 years. I have already tested whether the number ...
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37 views

How to model overdispersed percentage data?

this is my first post so let me know if you need more information. This is a pretty general question for now, but I am not sure how to approach this. The data I have is from an ecological study. In ...
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10 views

Analysis of proportional data (Two-factor design)

I did an experiment looking at damage to marine organisms as a result of fishing. I sampled in three vessels A, B and C. In each vessel I sampled the catch before on-deck handling (Pre) by fishermen ...
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1answer
59 views

Proper Number of Clicks for Conversion Rate Testing

I need to track the conversion rate of a landing page. I want to figure out how many clicks I need to get before I can be sure that I have an accurate conversion rate calculation. I first figured I ...
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1answer
35 views

Comparing proportions in the same sample

I gathered 11 responses to a question where the options were A, B, or C. 9 people answered A. 2 people answered B. 0 people answered C. Using Clopper-Pearson 95% confidence intervals, I obtained ...
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36 views

Exploring properties of groups in R

I have a data frame with the following structure: ...
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1answer
70 views

Using R's prop.test function to compare subsets of a population

I'm new to CV, so please excuse any faux pas. I've collected sample data from a population and would like to discern whether or not the experimental group outperforms the control group. Let's say I ...
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2answers
50 views

Confidence interval for Population proportion

I've a small query and really confused as how to solve such problems. $n$ people are question about internet connection 87 of them have high speed connection. We are given confidence interval(CI) of ...
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2answers
93 views

Kruskal-Wallis?

I have three sets of data (1 set before treatment, second during treatment and the third after), each of which consists of hundreds of trials on a specific task that involves choosing 1 from 7 ...
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1answer
66 views

Logistic regression: can weights be used as a predictor variable?

I counted the number of birds in a flock, which gave counts like these: ...
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30 views

Change in Proportion - Multiple Periods

So I have data consisting of a binomial variable observed in multiple time periods and I want to use a statistical test to determine the existence of a change over time. So here's how it looks: ...
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14 views

Comparing patient proportions between one ER and the national average

I am looking to compare the proportion of emergency room attendances by hour of the day against a national average proportion (plus some other tests for ER variables such as referral methods and ...
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147 views

ANOVA on percentages

Please read edit 3 first I am trying to find out the significant factors in a dataset of percentages, a sample of which are below. The difficulty is that the data violates the assumptions of ANOVA, ...
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94 views

Large overlap between confidence intervals, although z test for difference was significant

I have calculated a z test to examine the difference between two proportions. I found differences to be significant. The formula I used was: $$z = (p_1-p_2)/SE$$ where $$SE = \sqrt{ p ( 1 - p ) ( ...
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15 views

Confidence interval on Poisson distributed data

We have events which has different durations. I'm now computing confidence interval on defective events, meaning the ratio of events having encountered an issue. I consider this problem as counting ...
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0answers
72 views

Appropriate GLM when response variable is proportion, but not binomial

The response variable I'm dealing with is the proportion of a total area that is suitable habitat for a species of interest. So although the response variable is bounded between 0 and 1, my intuition ...
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51 views

Post-hoc analysis of 3 sample prop.test

I am looking for the correct way of performing post-hoc analysis on the results of a 3-sample test for equality of proportions and haven't been able to find anything specific to this test. The data I ...
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1answer
171 views

Confidence interval for probability equal to 0

I meet this real life problem. The simplified version is this: Assuming I have 10000 apples, either good or bad. What is the sample size if I want to be 95% sure that all the apples are good?
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32 views

Proportions (compositions) in logistic regression

I have a logistic regression where some of the independent variables are proportions (compositions) that sum to 100 percents. Let's say that I have 4 such variables - I have ran the regressions 4 ...
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1answer
43 views

How can you define below average, average and above average according to percentile rank?

A particular school evaluation lists abilities by percentile rank against the abilities of a population, and each ranking/ability is then given a group ranking of "Below Average", "Average", or ...