Questions tagged [percentage]

Number or ratio expressed as a portion of 100

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75
votes
5answers
82k views

Percentile vs quantile vs quartile

What is the difference between the three terms below? percentile quantile quartile
41
votes
10answers
9k views

Why is 600 out of 1000 more convincing than 6 out of 10?

Look at this excerpt from "The study skills handbook", Palgrave, 2012, by Stella Cottrell, page 155: Percentages Notice when percentages are given. Suppose, instead, the statement above read: ...
21
votes
4answers
9k views

Is 50% 100% higher than 25% or is it 25% higher than 25%?

If I have two values A and B which are both expressed as a percentage of C, and I want to express the difference in magnitude between A and B as a percentage D, is it more correct to express D as a ...
10
votes
3answers
8k views

What are the issues with using percentage outcome in linear regression?

I have a study where many outcomes are represented like percentages and I'm using multiple linear regressions to asses the effect of some categorical variables on these outcomes. I was wondering, ...
9
votes
1answer
3k views

How can percents not adding up to a hundred be possible?

I was reading this paper about aquaponics and some of the stats did not make any sense with regard to the percents listed. What method would allow these percents to exist? The most commonly raised ...
8
votes
1answer
488 views

Can a standard deviation of raw scores be reported as a standard deviation of percentages?

Suppose we have a test consisting of 30 questions, and 10 people take this test. The mean test score of these 10 people is 17, and the standard deviation of all the scores in the sample is 4. When ...
7
votes
4answers
1k views

Dungeons & Dragons Attack hit probability success percentage

In D&D players roll a 20 sided die trying to beat a set number to determine if an attack hits the target. Players often can add modifiers to this roll to help the odds in reaching this target ...
7
votes
2answers
10k views

What regression model to use when independent variables are percentages to predict % outcome?

"Independent" variables: time spent (% at work, % sleeping, % exercising), body mass composition (% fat, % muscle, % bone) Dependent variable: Smoker (1) or Non-Smoker (0) What kind of regression ...
6
votes
1answer
6k views

Mixture of beta distributions: full example

I have a vector of measured proportions and want to test if these proportions follow a bimodal distribution characterize the two underlying distributions determine for each data point which ...
6
votes
5answers
12k views

How to convert sport odds into percentage?

I am wondering how to convert sport odds to the percentage format. There's this example: ...
5
votes
3answers
16k views

Should percentages be reported with decimal places?

When presenting data using a percentage, is it a good thing to have decimal places, say 2 decimal places instead of rounding off to whole numbers? For example, instead of 23.43%, you round off to 23%....
5
votes
2answers
4k views

Is it correct to model percent change as a continuous variable?

I have data from a longitudinal study where there are 46 subjects, each with 13 observations over time on a given outcome measure. A prior analysis conducted on this data performed a linear mixed ...
5
votes
0answers
141 views

Which approach can be used to regress sleep time on brain mass, in this data set?

I was reading this blog post: https://htmlpreview.github.io/?https://raw.githubusercontent.com/avehtari/BDA_R_demos/master/demos_rstan/sleep.html the author describes a model to predict how many ...
5
votes
2answers
328 views

How do I test difference in Percentages?

I have some survey data and know the number and percentage of "yes" responses. How do I determine if any of the percentage yes regional responses are statistically different from the national yes ...
4
votes
1answer
261 views

Deal with percentage data

For instance, I have such data: ...
4
votes
1answer
146 views

Judging the quality of a statistical model for a percentage

I have a data set with multiple predictors, and a single response variable which is a percentage, thus is bounded between 0 and 100. I cannot share the dataset unfortunately. I would like to build a ...
4
votes
1answer
5k views

ANOVA on percentage data

I am confused about when I can and/or cannot run an ANOVA on percentage data. MY situation is as follows: I have two separate treatment groups (T1 and T2). Each of these treatment groups receives 1 ...
4
votes
2answers
1k views

How to analyze percent data when most of the data is 0%?

I have a set of percent data on histological abnormalities in fish gills and I need to compare the results between two sites A and B. We analyzed abnormalities in lamellae of a particular gill arch. ...
4
votes
1answer
2k views

Percentages as the response variable in GLMM (glmer), proportional binomial or not?

After looking through several questions on stackexchange, and even applying many of the suggested methods I have come to a point where I would like to have an expert's advice if the methods applied on ...
4
votes
1answer
16k views

How to calculate the Standard Deviation of a set of Percentages

I would like to know how to calculate the standard deviation (SD) of a set of percentages. Let me explain better. Some students performed a test and I counted the number of right answers for each ...
4
votes
1answer
5k views

Is taking the median of a set of percentages statistically sound?

I have several sets of data, unfortunately the data comes to me in a "summary" form. My job is to consolidate the several data sources into one general summary. I'm currently using the median to ...
4
votes
0answers
55 views

Rank forecasting from uneven samples

Say we have a bag of chocolate balls. There are $I$ different unique colors. Our bag has an unknown number of balls for each color. We want to get a sense of which color people like the most and ...
4
votes
0answers
6k views

Comparing two percentages

How would I go about comparing two percentage figures from two different sample sizes? For example: Sample 1 - 10% (220,510 out of 2,205,100) of respondents answered "yes", Sample 2 - 31% (12 out ...
4
votes
0answers
578 views

Percentile vs Percentile rank

I have the read the definitions many times and I still don't quite understand the difference. This article says: A statement such as: "A score of 600 has a percentile rank of 80" has a ...
3
votes
2answers
679 views

Dealing with Heteroscedasticity in ANOVA

I need to perform an ANOVA on percentages data. I have 3 factors: TREATMENT, SAMPLE and DaysAfterTreatment (DAT). Treatment has 3 levels: Control, A, B. SAMPLE has 2 levels: SampleA, SampleB. DAT has ...
3
votes
3answers
240 views

I know the probability of an event to occur, so how do I find how many times the event must be attempted to get a reasonably chance of success?

If there is a 2% chance of event X to occur, how many times must X be attempted to have a reasonable probability of occurring at least once? What is the formula used called, and how do I solve this?
3
votes
2answers
269 views

Normalizing sample sizes to identify trends

Every month I send out an email to prospective customers. The client I use tracks the number of recipients and the percentage of the emails that were opened. Here's a sample, there's thousands of ...
3
votes
1answer
398 views

How to properly display changes in percentages over time?

Our company is developing self-learning software that extracts data from documents and enters it automatically into text-fields in some other software, on behalf of the user. These suggestions aren't ...
3
votes
1answer
612 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 ...
3
votes
1answer
1k views

How to test for a statistically significant difference between 3 percentages?

I have samples of stories from three newspapers, all testing for the same proportion of stories with a certain characteristic. The data I have is: np1=16.34%, np2=14.00%, np3=18.29%. I want to ...
3
votes
1answer
872 views

How to test if a percentage is significantly higher than 0?

I have asked people to rate different items between 0 and 100. On one condition, most of the items were rated very low. Therefore, the distribution of the result looks like an negative exponential. ...
3
votes
1answer
87 views

How to deal with a response variable calculated from added percentages

I am analyzing a data set where the response variable is the total non-native plant cover within a plot. There are non-native grasses and non-native herbaceous plants with overlapping canopies, so the ...
3
votes
1answer
42 views

Difference vs log-difference: do they behave similarly?

Consider two positively-valued time series, $\{X(t),Y(t)>0|t\geq0\}$. Now consider two transformations: $$ U(t) = Y(t) - \beta X(t),\\ V(t) = \ln{[Y(t)]} - \ln{[\beta X(t)]}, $$ with $\beta>0$ ...
3
votes
1answer
2k views

Calculate the average rate of population increase per decade of a country

The population of a country increased by 20% in the first decade, 30% in the second decade and 45% in the third decade. What is the average rate of increase per decade in the population? The answer ...
3
votes
2answers
460 views

Modeling a non-stationary bounded series

I'm trying to model a time series variable that represents a percentage, strictly bounded between 0 and 1, that is also non-stationary about the mean. Is there a model form that is able to account ...
3
votes
1answer
78 views

Weighted average factor change

Let's say, we have some product in an online store, which overall rating calculates by weighted average of the following sub-ratings left by customer: ...
3
votes
1answer
544 views

Best way to analyse percentage data

I have percentage data and would like to see if these different variables have an affect on certain factors; i.e., I have different habitats of an area e.g., improved grassland: 40%, arable: 15%, ...
3
votes
1answer
30 views

Significance Between Two Percentage Decreases Over Time, Not Mutually Exclusive Variables and Different Sample Sizes

I work in an healthcare improvement department. I have spent a large amount of time looking for the best way to test this problem for significance and have come up short. If you take a look at this ...
3
votes
0answers
68 views

Comparing Percent Changes

I want to present information in the "most unbiased" manner possible: State XYZ increased GDP by 5.0 % last year The US increased GDP by 1.0 % last year Is there any (statistical?) bias in the ...
3
votes
0answers
2k views

Confidence Interval for a Percent Change

A mentor has asked me to calculate the 95% confidence interval surrounding a percent change. To help frame the question, I have calculated the incidence of a disease within the population as follows: ...
2
votes
1answer
69 views

Do equal percentage changes mean perfect correlation?

Consider two datasets, say time series $\{X(t),Y(t)|t\geq0\}$, and that the two experience an equal percentage change from one period to the next for all time. That is, if there is an $\alpha \%$ ...
2
votes
3answers
4k views

Comparing the age distribution of two groups with different sample sizes

I have a dataset regarding a hotel. I am trying to compare the age distribution of two groups: Leisure and business. The sample sizes of these groups are not equal. The business group has 12.4k ...
2
votes
1answer
1k views

Interpreting odds ratio of an ordinal regression when independent variables are negative percentages

I'm trying to express the results of an ordinal regression with a certain "perspective", and I'm confused. My dependent variable is an ordinal representing the progression in a scale of negative ...
2
votes
2answers
9k views

transformation of percentages (and eventual display)

I have some percentage data derived from the analysis of grain presence and absence in ears of wheat that have undergone two treatments (control and heat stress). For example, data might be like 10%, ...
2
votes
1answer
2k views

Power Calculations using “Percent Change” vs. “Absolute Values”

Percent change can be extremely misleading for a number of reasons (e.g. regression to the mean), even though in the medical literature percent change is used quite frequently to "normalize" clinical ...
2
votes
1answer
40 views

Term for rate of approaching 1.0?

I need to know the accepted term in statistics of a certain concept. What is the term for the following? When percentages change over some variable like time, it is referred to as a growth rate. ...
2
votes
1answer
29 views

Calculating per cent improvement in test error

I’ve come across this statement regarding an improvement percentage and I don’t know if it’s okay. It says this: The training error and test error using the neighborhood model are 0.34 and 0.54 ...
2
votes
1answer
65 views

Modelling a percentge as a dependent variable

I have a dataset containing 4 variables: Y - the dependent variable. This is a percentage of students in a school that choose to take an external exam. The values vary from 20% to 70%. X - the ...
2
votes
2answers
124 views

Choice of transformation for my data set

My data set contains the percentage cover of various plant species, on a rocky substrate. The problem I am having is that the substrate was often completely bare of any plant life. Due to this, a ...
2
votes
1answer
102 views

What test should I use if I want to compare 2 percentages?

I've got this hypothesis "People are better at detecting a lie when they are able to see a persons expression, compared to people that are not". I've tested 2 groups of people: 1) one group of 20 ...