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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Dealing with zeros when computing proportional change

I have a list of non-negative reals containing information for each day, e.g. rainfall on a given day, and I'm interested in computing the proportional change from day to day: $$ ...
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10 views

Testing Proportions of People Over Time

Let's say we have two time points (2013 and 2014 for sake of argument). In 2013, 50% of customers who come to my shop buy milk (100 out of 200 customers). In 2014, 75% of customers who come to my ...
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424 views

What is this diagram called

Can anyone tell me what is the name of this type of diagram ( if any )? Also can anyone suggest any tools, however simple, to plot such a diagram?
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29 views

Zero-and-one inflated beta regression vs. binomial GLMM?

I appreciate some help with deciding whether I should (and how to) construct a zero-and-one-inflated beta regression model. I want to use R to test the hypothesis that there is a ...
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9 views

Questions on same sample, significant difference on proportions?

I need some help with choosing the right statistics to use in the following cases.. especially the first one. Wish someone can help. select 1000 sample students out of a population (>10000), 300 get ...
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18 views

Post-hoc calculation of mixing proportions in gaussian mixture model

I have a Gaussian mixture model but without mixing proportions (weights). Is there a way to estimate the mixing proportions? One very crude way would be to obtain cluster assignments for the data ...
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1answer
25 views

Test for proportions - which one to choose?

I have a general question regarding proportions. Let's say, for simplification of things, that I have 2 groups of subjects (treatment and control), and for each subject I measure success or failure (0 ...
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48 views

T tests on proportions - Wrong, but how wrong?

In psychology, and probably a number of other disciplines, it's common practice to test between-groups effects on a binary variable, such as accuracy, by aggregating data within participants, and then ...
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1answer
55 views

How to calculate the standard error of a proportion using weighted data?

I know the "textbook" estimate of the standard error of a proportion is $SE=\sqrt{\frac{p(1-p)}{n}}$, but does this hold up when the data are weighted?
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40 views

Modeling proportions of autocorrelated binary data

I have data on infant crying for three time periods -- 1994-1996, 2000-2002, and 2010-2013 -- with about 15 infants per year. Each infant was observed every minute for 1080 minutes (across 3 days). If ...
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1answer
33 views

Test of proportions or chi-squared? [duplicate]

These data are from an A/B test of free trials to conversion. Someone can sign up for a 30 day free trial of the product. If they like it they stay on and become paying customers. By default (A), ...
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66 views

How to test the difference in two proportions when the outcomes aren't binary?

An e-commerce website is testing two different designs for a checkout page. Customers who visit the checkout page are randomly presented with one of the two designs. The first metric of interest, ...
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22 views

What to do after a significant Exact test?

I have significant Fisher exact tests for a 2x3 and 6x3 contingency table. All I can get from it is that the observation regarding columns and rows are not random. But I don't know which combination ...
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19 views

Apples & Oranges?: Weighting Individual Rates to Calculate An Overall Hit Rate

Imagine that you have a training program. This program graduates 1,000 students. 350 of these student seek continuing education after graduation, and 650 seek immediate employment. Of those 350, 212 ...
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21 views

Sample size for a small proportion

I'm calculating the required sample size for the following RCT design: the baseline proportion is 3%, and I want to be able to detect a difference of 1ppt with 80% power. If I use the sample size ...
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1answer
350 views

Why doesn't a sample proportion also have a binomial distribution

In a binomial setting, the random variable, X, that gives the number of successes is binomially distributed. The sample proportion can then be calculated as $\frac{X}{n}$ where $n$ is your sample ...
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31 views

linear vs. logistic regression on proportions

I simulated multiple datasets resulting in an average 2x2 contingency table (to analyze decisional accuracy they contain true scores and observed scores) over 500 replications of 1000 subjects for ...
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7 views

Figure out geographical distribution of ecommerce buyers

I am a total noob at this kind of thing. Will appreciate detail and links to tools to hold my hand through this. (Or even a consulting service that can help.) Context: I need to figure out a flat ...
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55 views

paired t-test… for proportions?

I did a pre-education and post-education quiz for a group of anonymous individuals. Individuals took a 2-3 question quiz, viewed an educational video, and then took another 2-3 question quiz. The quiz ...
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1answer
83 views

R: prop.test - Chi-squared approximation may be incorrect

I am trying to compare the proportions of two populations, using prop.test My data is straightforward - first population is 6/26 and second is 15/171. I am trying ...
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28 views

Comparing categorical outcome variables in repeated measures design

I am working on an observational prospective longitudinal study with a repeated measures design. The same categorical outcome is measured for five times, for all the participants, over a time period. ...
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27 views

Best method for predicting a numeric response from multiple proportional predictors?

I have some data where I want to predict a continuous, approximately normally distributed response/dependent variable with three predictors which are all proportions (i.e. 0-1). The three proportions ...
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1answer
18 views

Test of single proportion - how do i know population proprotion?

I have a study where I did a sample size calculation using N=2800, CI=95%, margin or error = 3.5% to yield n=613. In the study (auditing of charts), I wanted to look at the error rate in my sample. I ...
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12 views

Allocation of product with ANOVA or something else (?) in R - what direction and tests to use?

Assuming a very simplified view of my data looks like this: ...
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22 views

How to find changes in proportions using regression?

I want to test the hypothesis that the expansion of lending institutions changed the goals that households obtained their loans for. In other words, say in 1950 the breakup was: 33% got loans for ...
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63 views

How did they power this study? (One sample proportion test)

I was asked to perform a sample size calculation for a study with a single arm and a binary outcome. They have given me an assumed proportion, $p$, and need the upper 95% confidence interval to be ...
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1answer
28 views

What's my population? Is this Descriptive or Inferential?

I have a list of employees at a company. I want to show some comparison of some demographics (say, %female) of those who have left the company and those who have stayed with the company. However, I ...
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25 views

What method is appropriate? - analysing patterns of attacks by region

I am currently working on a project using a dataset on global terrorist attacks. For each attack there are details on the type of attack which has 7 levels (e.g. bombing, assasination etc.), the ...
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1answer
46 views

Hypothesis test of 2 proportions, with $np < 5$

We are frequently conducting one-tailed hypothesis tests for 2 proportions ($H_0: p_1-p_2=0;\, H_1: p_1-p_2 > 0$). However, $p_2$ is relatively small in terms of $n, x$ and in some cases we find ...
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45 views

how to test equality of proportions at different times

Here is my question. 20 (worm) mothers produce males + females and hermafrodites (many every hour). I want to test if the proportion of males + females born on day #1 is the same as in days #2 and ...
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1answer
16 views

Proportion test with null hypothesis p1=x*p2

I'd like to compare the proportion of two sets of binomial data where the null hypothesis is not p1=p2, or p1-p2=x, but \begin{equation} H0: p1=x*p2 \end{equation} I've been computing a z test as ...
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22 views

Assign the tree species most representitive of a specific size class

I am replicating another study in which trees were assigned to a class based on diameter. The most representative species of each class was identified for each plot sampled. The classes are sapling ...
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2answers
57 views

Compare official population distribution with sample?

I have official numbers regarding the population of specific ZIP codes that belong to a certain region, e.g. 90210 has population of 20.000 (just an example). (The set of ZIPs comprises a city and its ...
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1answer
71 views

Modeling a proportion using longitudinal data

To illustrate my question I'll make a (very) fictional example. I have a set of 17 year old people that every year report how many cigarettes they smoked and how many miles they ran. Very few of ...
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1answer
203 views

Probability distribution for a proportion based on (continuous) quantities

I have a problem related with probability distributions and parameter estimation, which comes from a real case. I would be very grateful if you could help me. Let us suppose that we have a continuous ...
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1answer
34 views

Is difference in proportions due to sample size?

I am currently working for a project team that is trying to reduce the number of defective parts produced in a factory. Without going into too much detail, the plant has a safety procedure where they ...
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1answer
41 views

Comparing rates of success in paired groups of samples

I have $2n$ paired populations, on which I measure a rate of success, let's say $(r_{group}^i)_{group \in (0,1)}^{i \in[1,n]}$ where $r_0^i$ and $r_1^i$ are the rates of success in the $i$-th pair of ...
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1answer
46 views

Fairness of a Coin

A coin is tossed $40$ times. Define $T$ as the number of tails. i) Define the region of rejection by $|T-20|\geq5.$ Calculate $\alpha,$ the significance level --- $\displaystyle\alpha = P(y\leq15 ...
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36 views

Appropriate test (in R) for proportion data that aren't normally distributed, aren't based on counts, and include 0's and 1's?

I'm studying differences in tree health among 5 species of trees across 3 different green infrastructure types. Here are the first few lines of data: ...
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13 views

Sampling comparison groups based proportionality versus real-world frequency

I am looking at differential gene expression (using a t-test) in the context of five Breast Cancer Subtypes. I am working with data in which the distribution of subtypes matches real-world frequency ...
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35 views

How to interpret parameters of GLM with binomial family for proportions

I would like to use glm with binomial family for proportions. However, I am wondering how could I interpret the parameters that is important in my case. In binary logistic regression one can interpret ...
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1answer
31 views

Can a proportion confidence interval be thought of as error of estimation?

One interpretation of a confidence interval for a mean is that the most plausible position of the mean (given no more information) is in the middle of the confidence interval, and the plausibility ...
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11 views

paired subject design test of proportions

I am analyzing a performance data set and would like to compare across two different conditions. I have three subjects, which were tested over a number of trials. Each trial had a chance of being in ...
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39 views

Comparing differences of ratios in 2 independent populations

I have a setting that I think is quite similar to the one described in What type of statistic should I use to compare ratios in my experiment?. I have two independent populations, which were screened ...
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1answer
50 views

McNemar's Test for repeated sex ratio data

I have proportion data (sex ratio of a dioecious plant) for a population that was measured three times. I would like to know if a McNemar's Test is the most appropriate analysis to answer the ...
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30 views

Post-hoc test for prop.test with 3 samples

I am performing a prop.test() in R for 3 different groups (samples). The result is a p-value that tells me that the observed proportions differ between the groups. --> How can I now find out whether ...
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60 views

weight of sample sizes in quasi-binomial GLM for proportion data

I'm studying a colonial organism, and my hope is to compare differences in percent survival between three treatment groups. The results are clear, there is a 55% difference in survival between ...
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1answer
170 views

Are different p-values for chi-squared and z test expected for testing difference in proportions?

I'm trying to test the difference in proportions using the z test method and chi-squared method, but am getting very different answers. Is that normal? My data: ...
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1answer
37 views

Prop.test alternative

I want to test if the proportion estimated by (600/100000) is less than 0.6. With prop.test(600, 100000, p=.6, alt="greater", correct=FALSE), p-value = 1. With ...
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1answer
58 views

Is Chi-square the right test to use when comparing multiple proportions

In my analysis, I have 4 groups: FLU-P (symptoms with virus) FLU-N (symptoms without virus) HCY-P (healthy with virus) HCY-N (healthy without virus) I am looking at the level of antibody ...