Tagged Questions

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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modeling a proportion with seasonality removed

I have a time series of proportions that typically fall in the 0.01-0.05 range. I had intended to use GLM to model these proportions, but I ran into trouble when I needed to first remove a strong ...
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1answer
16 views

Confidence Interval for the average of a set of proportions

If I have a dataset of 500+ observations (people in this case) that has the % of allotted dollars that were spent for each person (so, I have each persons allotted dollars and their dollars spent), ...
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14 views

Population proportion and confidence interval estimation

Q. A disease can be classified into four types. A random sample of size n=100 patients contains $n_1=70$ patients with type 1 disease, $n_2=10$ patients with type 2 disease, $n_3=15$ patients with ...
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8 views

multilevel mediation with a proportion dependent variable sem

I am attempting to test an indirect path in a multilevel dataset with an outcome that is a proportion. The data are a collection of variables related to various qualities of potential support ...
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18 views

Confidence interval for proportions for different patients

Question: Schizophrenia and other psychoses are complex and debilitating diseases, which affect about 2% of the population. Two of the approaches used, as well as in other medical diseases, to reduce ...
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1answer
29 views

Questions about non-standard test statistic for difference of two population proportions

Background I'm considering the number of observed 'successes' $x_1$ and $x_2$ from $n_1$ and $n_2$ independent trials respectively. These counts can be considered realisations of random variables ...
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20 views

Confidence intervals of proportions for clustered data

I am trying to compute the proportion of "yes"'s in data that is clustered (participants within cities). If I ignore the cities, I get very nice and narrow confidence intervals. If I compute the ...
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13 views

Estimating proportions in a non-nested multilevel Bayesian model

Data: x: 1/0 successes (~ 800 data points) c: city code (1 to 78) t: "time of measurement", 1 (morning), 2 (afternoon), 3 (evening), 4 (night) The problem: I would like to estimate the ...
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1answer
27 views

Three proportions testing null hypothesis

I have the following question. In a random sample of 250 people with low incomes, 155 are in favour of a new piece of legislation, while in random samples of 200 people with average incomes and 150 ...
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6 views

Scaling Specificity to larger data set

Suppose I have the following 2x2 table ...
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12 views

probability of sample proportion

I am trying to find the z-score for a sample proportion of 0.39 (The question is actually asking to find the probability of the sample proportion that is greater than .39). The only information ...
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1answer
15 views

Measurements from two raters. Should I use multilevel/“random-effects” model?

I have several variables that were measured on patients, for most patients the variables of interest were measured by 2 independent "raters". Most of the variables are binary. I need to compute the ...
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10 views

Rate of change of sub-population relative to that of the whole population.

I have data for the population size of a community, every five years for the last sixty years. The size of the population fluctuates, but generally increases over time. I suspect however that the ...
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2answers
47 views

Hypothesis testing: difference between proportions

I am investigating staff inequality between genders and ethnicities in an institution. I have data on contract types (permanent or fixed term) and pay grades for almost all employees. I want to test ...
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0answers
20 views

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 ...
1
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1answer
18 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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35 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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46 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 ...
2
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1answer
26 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., ...
3
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1answer
80 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
35 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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0answers
6 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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0answers
22 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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0answers
14 views

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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2answers
71 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
24 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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0answers
33 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
46 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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32 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 ...
2
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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
55 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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0answers
30 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
160 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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0answers
40 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 ...
3
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1answer
38 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, ...
1
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1answer
32 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 ...
3
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1answer
78 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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2answers
77 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 ...
3
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1answer
149 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
25 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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0answers
17 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 ...
2
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1answer
289 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 ...
2
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1answer
22 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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0answers
40 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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0answers
11 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 ...
4
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1answer
64 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 ...
2
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1answer
37 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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38 views

Exploring properties of groups in R

I have a data frame with the following structure: ...