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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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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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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33 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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8 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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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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23 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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13 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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27 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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40 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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37 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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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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24 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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31 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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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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121 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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15 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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50 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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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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29 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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51 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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Independent Categories with multiple responses, chi-square too simple, MRCV log-linear model too complex?

Hello all and thanks in advance for your consideration, My research question is simple: Do lynx have a different diet in summer compared to winter? Data structure looks simple at first glance, ...
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31 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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33 views

Exploring properties of groups in R

I have a data frame with the following structure: ...
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52 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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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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82 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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63 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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27 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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12 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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138 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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2answers
74 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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60 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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43 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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170 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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30 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
36 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 ...
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71 views
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How to calculate the confidence interval for a combination of a proportion and continuous data

I want to calculate the 95% confidence interval for a combination of binary data and continuous data. Lets say I want to estimate the production of a certain item from all factories of a given ...
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1answer
52 views

Course of Action for 2x2 tables with 0's in cell and low cell counts

I'm comparing two groups A, B after cross tabulating them with cases and controls. I get a table as such: Control Cases A 8 0 B 14 0 ...
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I'm in over my head, need help on specification

I am carrying out an exploratory regression looking at the determinants of corporate governance. The final model is: Board independence= Country Dummies+ Democracy level+ Sector dummy+ log GDP+ ...
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29 views

Finding P Value of Two sample hypotesis test for Proportion

I am attempting to find the P-value of a hypothesis test, which compares the success rate of two procedures. A test with 0.05 level of significance is conducted to test the success rate of two ...
2
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1answer
66 views

Question on Probability

I was attempting to solve a question on finding the probability that a randomly selected person had an income of $50,000 or more would be audited, based on information on the table below: My ...
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32 views

Comparing proportions

I have a sample of 65 participants. 20 chose A. 18 chose B. 14 chose C and 13 chose D. What is the suitable test to determine if there is significant difference in the proportions?
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109 views

2 sided vs 1 sided test

I am asking this questions straight from "Data Analysis and Statistical Inference " course by Dr. Mine Çetinkaya-Rundel on coursera! Please right click on the image and one in a new tab to make it ...
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28 views

Detecting heterogeneity in groups

This is a mockup of a dataset I am currently working on: ...
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37 views

Difference test between 2 groups where both groups contain depended and independent observations

Is there a statistical test to check the difference between groups (for example a paired sample proportion test), but where some of the observations of the two groups are dependent and some of the ...