Linked Questions
23 questions linked to/from Why is the square root transformation recommended for count data?
62
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6
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A chart of daily cases of COVID-19 in a Russian region looks suspiciously level to me - is this so from the statistics viewpoint?
Below is a daily chart of newly-detected COVID infections in Krasnodar Krai, a region of Russia, from April 29 to May 19. The population of the region is 5.5 million people.
I read about it and ...
- 1,213
55
votes
4
answers
8k
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How do we decide when a small sample is statistically significant or not?
Sorry if the title isn't clear, I'm not a statistician, and am not sure how to phrase this.
I was looking at the global coronavirus statistics on worldometers, and sorted the table by cases per ...
- 885
34
votes
6
answers
25k
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Line graph has too many lines, is there a better solution?
I'm trying to graph the number of actions by users (in this case, "likes") over time.
So I have "Number of actions" as my y-axis, my x-axis is time (weeks), and each line represents one user.
My ...
- 443
24
votes
5
answers
60k
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What could be the reason for using square root transformation on data?
What is the primary reason that someone would apply the square root transformation to their data? I always observe that doing this always increases the $R^2$. However, this is probably just due to ...
- 5,805
10
votes
3
answers
4k
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Choosing c such that log(x + c) would remove skew from the population
I have data for which I would like to take the log transformation before doing OLS. The data include zeros. Thus, I want to do a log(x + c). I know a traditional c to choose is 1. I am wondering ...
- 815
8
votes
2
answers
5k
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Log vs square root link for Poisson data in R
I am currently working to model deaths from AIDS over time using a GLM in R. I know that there are two possible options for the link function for Poisson data, log and square root.
I know that square ...
- 81
13
votes
2
answers
515
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Is visualization sufficient rationale for transforming data?
Problem
I would like to plot the variance explained by each of 30 parameters, for example as a barplot with a different bar for each parameter, and variance on the y axis:
However, the variances are ...
- 7,200
1
vote
1
answer
5k
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Understanding variance stabilization and its uses
I recently came across the variance stabilization method that tries to remove the dependency of variance from the mean (for example consider Poisson distribution). ...
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3
votes
2
answers
3k
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Model approach for count data with a large range of y values
I am modeling ridership data for specific routes by month over a number of years. Some routes have as little as about 1000 riders per month while other routes may have over 20,000 riders per month. ...
- 473
5
votes
1
answer
951
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When is it appropriate to apply a transformation?
I understand Box-Cox transformations, when to apply which transform (log vs exponential) and on what type of distribution (left vs right skewed). However, what I don't understand is when is it ...
- 171
4
votes
2
answers
1k
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Closest approximation of a Poisson GLM using weighted least squares analysis to take into account mean/variance relationship
I have an application where I would like to approximate a Poisson GLM with identity link, i.e. a glm of the form
...
- 3,080
7
votes
1
answer
704
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What is the specific issue with using count data for ANOVA tests
I'm running a study with a between-groups component and a within-groups component, with a predictor that is count data. I was planning on using split-plot ANOVA to analyze this, but after seeing lots ...
- 439
3
votes
1
answer
2k
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General Linear Model Univariate with unequal variances - what are my options?
I'm using SPSS to run a GLM (general linear model) univariate with 1 fixed factor (Treatment) and one random factor (experimental replicate). There are 4 treatment groups. The measurement is number of ...
- 41
1
vote
1
answer
1k
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log transforming a Poisson variable
Trying to understand how log-transforming a count variable changes the regression equation.
The reason I ask is because I see a lot of researchers log-transform their data so they can use OLS.
Say you ...
- 523
7
votes
2
answers
1k
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Population model to model year to year dynamics
My task is to assess how various environmental variables affect annual population fluctuations. For this, I would use a model like:
$$
\mbox{log} ( \mu_{i,j+1} ) = \mbox{log} ( \mu_{i,j} ) + R_{j} + \...
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