All Questions
Tagged with logarithm lognormal-distribution
18
questions
1
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1
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542
views
Getting (geometric) 95% CI from geometric mean and geometric SD (after log-transformation)
I am conducting a meta-analysis with a skewed distribution. To address this issue, I transformed the "marker" data into a log-scale, "ln marker".
I obtained the (geometric) mean ...
- 33
0
votes
0
answers
245
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How to adjust for lognormal distribution in linear regression when dependent variable is a ratio?
I am working on a model that uses a dependent variable (Damage ratio) that is a ratio composed of two other variables (Flood damage / market value). One of those variables follows lognormal ...
- 53
1
vote
1
answer
424
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Estimating the log-space sigma (std) parameter of a lognormal distribution from its regular-space mean and variance
validaters,
I've spent a lot of time on this issue and I can't figure it out yet.
So, a lognormal distribution is being defined as follow: X=e^(μ + σ Z), where Z is ...
2
votes
0
answers
809
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How to derive sales contribution in a log-log regression media mix model?
I am working on a media mix model to determine how different media channels impact sales.
Since there is a non-linear relationship between sales and media spend, I needed to apply a log transformation ...
0
votes
1
answer
491
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Expectation of log skew normal distribution
What is the expected value and expected variance of a log skew normal distribution?
In case I have the terminology wrong, I'm referring to data that is lognormal with some skew mild skew when it's log ...
- 372
2
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0
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121
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Why does the log transformation bring data closer to normal distribution? [duplicate]
Quite often in published research we see researchers apply log transformation to their data, and some claim that this makes the data closer to normal distribution. My questions are:
Mathematically, ...
- 2,966
2
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0
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147
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what is the distribution of the log of a normal distribution? [duplicate]
if you exponentiate a normal distribution,
Y=exp{X}
where X is a normally distributed random variable (RV), then Y is log-normally distributed.
What is the ...
- 1,084
1
vote
1
answer
2k
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For lognormal distribution which one is preferred? Log 10 or Ln or Log 2?
I want to perform a linear regression analysis. The distributions of data for all continuous variables are not normal. The tail of graph is to the right and thre highest point of graph is due to the ...
user241033
0
votes
1
answer
483
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Am I Log Normalizing correctly?
I have searched the other questions about log normalization and all assume a level of understanding that I don't have.
I have some ecological data and I am told that it needs to be log transformed. My ...
- 11
0
votes
1
answer
9k
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Log Transformation in R
I need to transform my not normal distributed data to normal distributed variables. Therefore I need to log-transform them. Log10(x+1) has not worked to create a normal distribution. Therefore, I want ...
- 11
4
votes
4
answers
2k
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Alternative to log when doing linear regression on multiplicative dataset with zeros
I'm doing work on a dataset that is approximately lognormally distributed, but with significant amounts of zeros (kinda like looking at forum post activity per subforum. For those who do post, the ...
- 1,724
3
votes
3
answers
3k
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log transformation for paired t test
If my difference scores are not normally distributed - and I want to do a parametric paired t-test - do I:
log transform the the original scores and perform a paired t-test on these scores
log ...
- 813
3
votes
0
answers
574
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Expectation of the log of a ratio of two lognormal random variables with additive constants
I have two independent lognormal random variables $X$ and $Y$ with known means and variances. I would like to know the expected value and the variance of $\ln\big((X+1)/(Y+1)\big)$. If there is no ...
- 41
0
votes
1
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1k
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Log of Ratio Results in Log-Normal Distribution?
I am trying to understand some chemical concentration data I have measured. I am taking the log of the ratio of two concentrations. The ratio itself is from oscillating timeseries data and is the (...
- 121
3
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2
answers
8k
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Transforming back after a log transformation
I have two datasets, one on which I have my covariates $X_1$ and my observed outcome $Y_1$, and one on which I have only my covariate $X_2$. I want to predict $\hat{Y}_2$. However, I have far better ...
- 1,197