Questions tagged [proportion]
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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Comparing the distributions of proportions in two groups
I'm comparing the total dog population in a region with the number of dogs in rehoming centres in that region. The data are below. The number of cases is the number of dogs that have been in rehoming ...
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Appropriate regression to predict >2 fractions?
Let's say I have demographic data on various classes and the proportion of students in the class who are black, white, etc. I'm trying to create a regression to determine features of the class that ...
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50 views
R: generalised additive model on proportional data
Introduction
I am analysing temporal population data on the amphipod Orchestia gammarellus. At several moments each year, all animals were collected from a small spot, and several life history traits ...
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9 views
Sample size for the normal approximation of the Binomial distribution
I am reading about the familiar hypothesis test for proportions, using the normal approximation for large sample sizes. Some people say (write) that the condition for using the approximation is np>5 ...
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1answer
23 views
Sample size needed to prove equal proportions
We are trying to prove that three groups have the same proportion of some effect. We are struggling with formulating the null hypothesis, and whether or not the sample size is big enough. The ...
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1answer
39 views
Proportion Test: Z-test vs bootstrap / simulation - different results
I'm learning hypothesis testing, and going through the following example:
The CEO of a large electric utility claims that 80 percent of his 1,000,000 customers are very satisfied with the service ...
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14 views
Overdispersed proportion test?
I am comparing proportions in genomic data. In particular, I compare two populations, A and B, and I look at genetic sites. In other words, I have N contingency tables
...
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Test for yield and disease incidence in block design
I need to analyse a set of data coming from an agricultural experiment, with the intention of assessing the incidence of a certain disease in potatoes under three different treatments (plus blank). I'...
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1answer
47 views
How to calculate the error of percentages
Is it correct to calculate the standard deviation of percentages/proportions as you would for four numbers (i.e. non-percentages)?
Thanks for your help @user2974951 @whuber and @asdf. Yes, you're ...
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1answer
26 views
Find significance between two group proportions
My question is the following: what statistical test would I use to compare the proportion of participants between two groups. For example, if in 2009, 20% of participants ( population was 55) to a ...
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12 views
group sequential design for one proportion
I would like to create a group sequential design for a one proportion to test H0: p=0.97 vs H1: p=0.98 with alpha=0.3 and beta=0.43.
Above specification provides me the sample size of 120 for a ...
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14 views
GLM for proportion data in r - with many zeros (or ones) [duplicate]
My understanding is that generalized linear modeling (GLM) is recommended for proportion data.
However, this seems to run into problems when a set of data is full of zeros (or ones). For example, a ...
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28 views
which stat test?
I am doing a health interventional study in the community. I calculate the "pre-intervention" proportion of behavior of the community before applying the interventions. And after 1 years of various ...
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1answer
20 views
Get better confidence interval by drawing multiple samples
Imagine that I have population of size N and I draw a sample of size n from which I compute a proportion $\hat{p}$ of a categorical variable.
And I want to get a confidence interval of 95%. So I ...
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105 views
Calculating a Confidence Interval for a Proportion for a Sample of Different Size
I'm interested in a (preferably analytic) solution or approximation to the following problem:
Let $s_1$ be a sample from an unknown distribution of size $N_1$ and with proportion of successes $p_1$. ...
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1answer
78 views
Comparison of proportions using McNemar's Chi-Square using Pre- and Post- data for two disease conditions
This question follows-up on the post: What is the difference between McNemar's test and the chi-squared test, and how do you know when to use each?
I am examining a pre- and post- intervention data ...
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1answer
21 views
Comparing proportions from overlapping samples
I'm looking to compare the read rate of an email newsletter with the read rate of another newsletter. However, many (not all) of the people who receive one newsletter also receive the other. What ...
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1answer
18 views
Test a proportion against unanimity
How can I test a proportion against an expected value of 1.0?
Made up example (slightly silly):
Dichotomous Yes/No question...
Would you like me to hit you very hard on the head with this hammer?
...
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25 views
Distribution for average of multiple binomial proportions
Assume we have a population $N$ and a proportion $p$ of that population with a characteristic of interest. Both $N$ and $p$ are unknown. Furthermore, assume that we have $k$ random samples $(n_i, x_i)$...
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Modelling percentage and proportion data with GLM's [duplicate]
I would like a simple answer, if there is one, to a question I cannot seem to find on here.
What is the best way to model percentages?
Say I have a glass that is empty and I fill it with liquid ...
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21 views
Comparing Test and Control Lift in Proportion
I have two groups - a test/treated and control group - for which I am trying to assess whether the lift or percent change in proportion from a pre to post period between the two groups are unequal.
I'...
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Comparing survival rates
The question I have is focused on comparing remission rates at a fixed point in time.
For example, I have cancer type A and cancer type B (the two are not mutually exclusive groups) and all patients ...
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1answer
28 views
Where is my potential flaw in my Z-test of Proportions?
I was working through this z-test of proportions example I found online. The online example solutions says that the difference between the groups is statistically significant, whereas I concluded it ...
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Is lmer or glmer appropriate for nested continuous proportion data
I have a reviewer that wants me to analyze my data along the lines:
Con_Ratio ~ Range * Latitude * Longitude + (1 | Genotype/Pair).
But I'm not sure if this can be done and how. My experimental ...
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0answers
38 views
specific equation for modified wilson confidence interval
I recently read the Brown, Cai, Dasgupta paper on interval estimation for a binomial proportion where they propose the modified wilson method as a better alternative to the standard wald interval. I ...
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1answer
29 views
Are there statistical tests for testing multiple sample proportion?
For categorical variable testing, we have chi-square test. For example, we want to test if a dice is fair (assuming sample has [6,5,7,7,6,5] and ...
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1answer
114 views
Time Series of Wound Healing percentages / proportions
I am looking at wound healing over time and have hit a wall with analysis. My data consist of injury cases which are tracked over time. Injury healing is measured as percentage wound area/perimeter ...
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1answer
34 views
What statistics test to compare the repartition of multiple choices between two groups?
I made an experiment about UX where the participant has to detect among five differents configurations the one that he prefers.
The configurations are slightly different and are presented randomly 3 ...
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11 views
Why don't we need to use a t-distribution for difference of proportions tests? [duplicate]
In difference of proportions tests we use a Z-distribution. And in Chi square tests which I understand are in practice the same test use the square of the Z-distribution, the Chi square distribution ...
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28 views
compare distribution a categorical variable between a population and a subpopulation
So I have the following situation of having a population P with individuals belonging to categorical variable A, ..., N. From this known population I created several sub-population P1, P2 (each time ...
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1answer
33 views
Standard error of a proportion on a 2 x 2 contingency table
Why on a 2 x 2 table such as
where $p = \frac{a}{a+b}$
the standard error of $p$ is
$$\left(\frac{(a+c)(b+d)}{(a+b+c+d)^2(a+b)
}\right)^{1/2}$$
?
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51 views
Should I use a binomial glm, beta regression, uniform continuous distribution or nls with logistic regression for probabilities?
I made an individual based model in which there is a population of three types of individuals (lizards) that disperse randomly until they encounter another individual that has a beneficial effect on ...
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103 views
Comparing proportions between multiple groups - Fisher's exact test
I have a simple dataset on reproductive success of a certain plant species. Reproductive success was defined as a proportion between number of flowers and number of fruits. We measured on 10 different ...
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21 views
Cochran's Q test with changing proportions
for my thesis I am investigating the change in proportions of children in regular and special education. The information is obtained through an online questionnaire, and I have data for 4 consecutive ...
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37 views
Statistical test for binned proportion data in JMP / MATLAB
I have been trying to determine the proper statistical test for comparing binned proportional data between groups. My data set is individual subjects (4-5 per group) with 76-165 cells per individual. ...
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1answer
31 views
Z-score for weighted proportion
I have a question regarding the Z-Score test when it comes to compare two proportions.
Usually, one would use this formula to obtain the Z-Score:
and then compare it to a Standard Normal ...
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0answers
36 views
Testing the goodness-of-fit for the binomial distribution
As specified in the title, I'm trying to understand how to test the goodness-of-fit for the binomial distribution; to this aim, I followed what suggested in this link.
Particularly, I'm investigating ...
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19 views
How do I model whether compositional data changes over time? [duplicate]
I have a data set of diet proportions over time (this is just a sample):
...
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0answers
15 views
Compare overall proportions between 2 samples
I want to compare multiple proportions between two samples. There are 60 brands of toys (T1, T2, T3...T60). I would like to know if overall, the proportion of respondents who own each brand of toy is ...
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0answers
10 views
probability to belong to the majority class based on observed proportions
I have a population of several categories and I don't know the proportion of these categories in my population. I want to draw (with replacement) in my population until I can say with 99% certainty ...
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1answer
18 views
How to report percentage change in proportions?
I want to compare changes in the proportion of fruit purchases over time for a household. For example, in year 1, 4/40 (10%) fruit were apples, in year 2, 12/80 (15%) fruit were apples.
When ...
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2answers
38 views
How to define sampling unit. t.test vs proportion test
In my particular case I am comparing damaged fruit in several treatment fields vs. several control fields
For simplicity:
Both treatment and control have 10 bushes each. a cluster of fruit is taken ...
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2answers
316 views
Regression when both the predictor and outcome variables are proportions
I am using
$X$ The estimated pre-game win probability of a sporting team playing on its Home field (estimated according to a certain model)
to predict
$Y$ Actual proportion of points scored by ...
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4answers
74 views
Frequencies/percentages different from zero - which test?
I conducted an experiment and had participants indicate binary judgments by either pressing "1" or "0" when seeing different types of stimuli. Now I want to test whether the proportions of number ...
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1answer
83 views
How likely is a random sample to be significantly similar to the full population?
I am looking for a way to compare the proportions between two data sets of surveys, where individuals can be placed in more than one classification.
One of my groups contains the survey results of 10....
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2answers
55 views
Calculating sampling proportion's standard deviation given population proportion?
So the question is as follows (paraphrased):
A population votes for/against a political candidate. In a sample of 200 voters, let $X$ be the fraction of people who vote for this candidate.
...
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1answer
51 views
Interpretation of variable in a probit model
I am struggling interpreting the coefficient of a variable which is expressed as a proportion in a probit model. As it currently stands , I am interpreting the average partial effects of this variable ...
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41 views
Chi squared test: which is the correct null hypothesis?
I'm reviewing some literature in my field, specifically looking at whether physical activity (PA) has any beneficial effects on cognitive performance. The results across the studies are quite mixed. ...
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1answer
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Bernoulli / binomial trials for a process with variable probability of success
One of the conditions for a Bernoulli trial (and by extension binomial proportion confidence intervals) is that the probability of success is the same every time the experiment is conducted.
In the ...
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1answer
31 views
Model proportions as independent variable for binary outcome
I've binary (disease) outcome: 0, 1 with certain independent variables in proportions, and other covariates as - age, sex.
There are Packages that model proportions as outcome variable but not other ...
