Linked Questions

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1answer
1k views

log transformation - negative values [duplicate]

I am trying to log transform time series data of Inflation. However, there is one negative value. I have added the constant 1 to all my values and the log transformed. ...
0
votes
0answers
50 views

Is it good practice to add 1 to 0 scores in log-normalization? [duplicate]

I am apply log-normalization to my non-normal data. However, when I apply log-normalization, the 0 values is converted into inf, which makes it impossible to apply ...
0
votes
1answer
44 views

Resolving skew and determining the back transformation function [duplicate]

I have a skew variable and I want to use box-cox transformation (log) but around 50 observation out of 200 are between 0 and 1. My initial thought was to add a constant to all observations before ...
0
votes
0answers
26 views

Log transform with 'zero' values [duplicate]

I am doing some explorative work on two large datasets. One from 2001 and one from 2018. The dataset consists of measured soil-parameters and it contains lots of zero's. From the transformations ...
0
votes
0answers
14 views

Can I add a constant and then transform my explanatory variable? [duplicate]

My current model is of the form $$\log(\frac{y_i}{1-y_i}) = \beta_0 + \beta_1 x_1+\beta_2 x_2.$$ Is it okay if I consider the model $$\log(\frac{y_i}{1-y_i}) = \beta_0 + \beta_1 x_1+\beta_2 \log(x_2+1)...
241
votes
148answers
128k views

Famous statistical quotations

What is your favorite statistical quote? This is community wiki, so please one quote per answer.
184
votes
11answers
130k views

How should I transform non-negative data including zeros?

If I have highly skewed positive data I often take logs. But what should I do with highly skewed non-negative data that include zeros? I have seen two transformations used: $\log(x+1)$ which has the ...
38
votes
1answer
31k views

Regression: Transforming Variables

When transforming variables, do you have to use all of the same transformation? For example, can I pick and choose differently transformed variables, as in: Let, $x_1,x_2,x_3$ be age, length of ...
21
votes
7answers
8k views

Combining probabilities/information from different sources

Lets say I have three independent sources and each of them make predictions for the weather tomorrow. The first one says that the probability of rain tomorrow is 0, then the second one says that the ...
36
votes
3answers
20k views

Regression for an outcome (ratio or fraction) between 0 and 1

I am thinking of building a model predicting a ratio $a/b$, where $a \le b$ and $a > 0$ and $b > 0$. So, the ratio would be between $0$ and $1$. I could use linear regression, although it doesn'...
6
votes
3answers
2k views

How to interpret this QQ plot?

I have ran a QQ plot on R on my data using par(mfrow=c(1,2)) par(pty="s") qqnorm(TEDS$LST1); qqline(TEDS$LST1) which gave me this: The histogram of the data ...
9
votes
2answers
8k views

Distribution for percentage data

I have a question about the correct distribution to use for creating a model with my data. I conducted a forest inventory with 50 plots, each plot measures 20m × 50m. For each plot, I estimated ...
4
votes
2answers
12k views

How to log transform data with a large number of zeros

I have a dataset comprised of continuous values that have about 30-50% zeros and a large range (10^3 - 10^10). I believe these zeros are not a result of missing data and are the result of the ...
5
votes
2answers
458 views

Alternatives to multilevel model with log transformed outcome

I'm working with linear mixed-effects model in Stata. Dataset has three levels of 100k observations, nested in 500 regions, nested in 70 regions. Currently my modelling strategy is to use three-...
-2
votes
1answer
5k views

How to perform boxcox transformation on data in R tool [duplicate]

Possible Duplicate: How should I transform non-negative data including zeros? Error in boxcox.default(y ~ x) : response variable must be positive I want to perform box cox transformation on ...

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