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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Beta distribution GLM with categorical independents and proportional response

My data is percentage disease data of different varieties of plants that had been inoculated with disease from several different sources. having conducted two-way ANOVA in SPSS (using the log10+1 of ...
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20 views

what is the intuition behind the SRSWOR formula?

I earlier asked about Slovin's Formula (http://math.stackexchange.com/questions/1410492/what-is-the-intuition-behind-slovins-formula), and learned shortly thereafter that it was derived from this ...
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16 views

Proportion z test for predictive model

I have deployed two models, the baseline one which only includes historical data of a stock market index and the twitter model which includes both historical data of the index as well as significant ...
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35 views

Testing the Validity of a Test Statistic (incorrectly)

In this post @Wolfgang shares a few lines of code to test in a simulation the ability of a particular test statistic to perform as expected, measured by the percentage of type I errors. He shows by ...
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29 views

How to calculate the sample size for proportions using Effect Size?

I need to determine the sample size for my experiment. In my experiment I will select a set of x projects, from a population of N project. For the sample x projects will apply a treatment to know the ...
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39 views

Test of Equal Proportions with exact p-values [duplicate]

The question "Test of Equal Proportions with zero successes" showed me that using a test of equal proportions with very low or very high numbers of successes doesn't give an accurate p-value. Below is ...
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18 views

Generating sample proportions when the true proportion is close to 1

Suppose the true proportion of success is $\pi$. I would like to generate sample proportions around $\pi$. I can use ...
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53 views

Test for difference in proportions with small probabilities

I want to perform a test for differences between 2 binomial populations. The probabilities are small (usually less than 10 %). I can define the successes as "rare events". I think that the z-test ...
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17 views

Beta regression with “random effect” of source plot in two seasons

I am attempting to model the effect of several continuous and categorical predictors on a continuous proportion response variable. My experiment had 3 treatments, which were replicated in each of 9 ...
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49 views

Paired Comparison Preference Test

From a real-life situation, but distorted enough to be untraceable... A cohort of patients (n= 300) were each one subjected to two procedures (...
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43 views

Test of Equal Proportions with zero successes

I'm testing if three independent experiments have the same probability of success ($H_0: p_1 = p_2 = p_3$). For $f_1 = f_2 = f_3 = 0$ and $n_1 = n_2 = n_3 = 10$ (zero successes out of 10 trials in all ...
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28 views

Why does changing the null hypothesis change the confidence interval?

Using my stat calculator, I don't see why if I do two different tests with everything the same but the null hypothesis, the confidence interval is different. For example: Has a different CI from ...
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17 views

what's the right way to combine binomial parameter estimates?

let's say you have a bunch of weighted coins. by observing flips, you can estimate (a confidence interval for) the binomial parameter for each. how should you combine these to summarize the ...
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comparing multiple proportions over time

I have a dataset of 22 fish species in a fish market, sampled monthly, from 2007 to 2011. I want to see if there is a statistically significant change in their relative proportions over time. I first ...
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15 views

Evaluating a proportion over time

How do I evaluate a proportion within a population over time? For example, a group of patients undergoes an intervention. Assessment of knowledge is obtained pre-intervention and post-intervention, ...
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10 views

Testing the difference between multiple paired proportions with different sample sizes

Is there a hypothesis test similar to the paired t-test for testing if the difference between a number of paired proportion estimates is significantly different from zero? The data consists of 2 lists ...
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3answers
377 views

Is it right to build a logistic model for population with 2% of yes and 98% no population with 800k obs and 200 variables

I have a dataset which has has some 800,000 observations data at member level with some 200 features and it has a response flag of 1/0. The proportion of response 1 flag is 2% of entire member ...
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6 views

Conducting a correlation when one of the covariates is a proportion

Is there anything that I should be wary of when conducting a correlation when one of the covariates is a proportion? I shall be running a Spearman rank analysis, correlating a continuous variable ...
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7 views

Single proportion estimation with correlated data

I have a sample of observations, each is either success or failure (0/1). The observations comes in pairs, i.e., each subject contributed 2 observations, for example, effect of ear drops, which were ...
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17 views

Dealing with zeros when computing proportional change

I'm attempting to investigate the independence of the proportion of dividend payouts which is not linked to the movement of the stock index. The data I have is in the form of a list of dividend ...
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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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643 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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39 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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10 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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22 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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26 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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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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78 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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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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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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68 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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24 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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22 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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354 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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33 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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8 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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60 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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105 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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42 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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29 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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19 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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24 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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83 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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32 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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26 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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48 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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50 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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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 ...