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1500 questions
76
votes
2 answers
Practical questions on tuning Random Forests
My questions are about Random Forests. The concept of this beautiful classifier is clear to me, but still there are a lot of practical usage questions. Unfortunately, I failed to find any practical guide to RF (I've been searching for something like…
lithuak
- 1,013
76
votes
4 answers
Is standardization needed before fitting logistic regression?
My question is do we need to standardize the data set to make sure all variables have the same scale, between [0,1], before fitting logistic regression. The formula is:
$$\frac{x_i-\min(x_i)}{\max(x_i)-\min(x_i)}$$
My data set has 2 variables,…
user1946504
- 1,337
76
votes
5 answers
How small a quantity should be added to x to avoid taking the log of zero?
I have analysed my data as they are. Now I want to look at my analyses after taking the log of all variables. Many variables contain many zeros. Therefore I add a small quantity to avoid taking the log of zero.
So far I've added 10^-10, without any…
miura
- 3,684
76
votes
8 answers
Clustering with a distance matrix
I have a (symmetric) matrix M that represents the distance between each pair of nodes. For example,
A B C D E F G H I J K L
A 0 20 20 20 40 60 60 60 100 120 120 120
B 20 0 20 20 60 80 80 80 120 140 140…
yassin
- 863
76
votes
11 answers
Is there any *mathematical* basis for the Bayesian vs frequentist debate?
It says on Wikipedia that:
the mathematics [of probability] is largely independent of any interpretation of probability.
Question: Then if we want to be mathematically correct, shouldn't we disallow any interpretation of probability? I.e., are…
Chill2Macht
- 6,249
75
votes
1 answer
How to split the dataset for cross validation, learning curve, and final evaluation?
What is an appropriate strategy for splitting the dataset?
I ask for feedback on the following approach (not on the individual parameters like test_size or n_iter, but if I used X, y, X_train, y_train, X_test, and y_test appropriately and if the…
tobip
- 1,570
75
votes
7 answers
Rule of thumb for number of bootstrap samples
I wonder if someone knows any general rules of thumb regarding the number of bootstrap samples one should use, based on characteristics of the data (number of observations, etc.) and/or the variables included?
hoyem
- 1,161
75
votes
6 answers
Do the predictions of a Random Forest model have a prediction interval?
If I run a randomForest model, I can then make predictions based on the model. Is there a way to get a prediction interval of each of the predictions such that I know how "sure" the model is of its answer. If this is possible is it simply based on…
Dean MacGregor
- 1,138
75
votes
4 answers
Linear model with log-transformed response vs. generalized linear model with log link
In this paper titled "CHOOSING AMONG GENERALIZED LINEAR MODELS APPLIED TO MEDICAL DATA" the authors write:
In a generalized linear model, the mean is transformed, by the link
function, instead of transforming the response itself. The two methods
…
miura
- 3,684
75
votes
6 answers
Model for predicting number of Youtube views of Gangnam Style
PSY's music video "Gangnam style" is popular, after a little more than 2 months it has about 540 million viewers. I learned this from my preteen children at dinner last week and soon the discussion went in the direction of if it was possible to do…
FredrikD
- 853
75
votes
4 answers
Standard error for the mean of a sample of binomial random variables
Suppose I'm running an experiment that can have 2 outcomes, and I'm assuming that the underlying "true" distribution of the 2 outcomes is a binomial distribution with parameters $n$ and $p$: ${\rm Binomial}(n, p)$.
I can compute the standard error,…
Frank
- 1,686
75
votes
7 answers
Do all interactions terms need their individual terms in regression model?
I am actually reviewing a manuscript where the authors compare 5-6 logit regression models with AIC. However, some of the models have interaction terms without including the individual covariate terms. Does it ever make sense to do this?
For example…
djhocking
- 1,931
75
votes
6 answers
Criticism of Pearl's theory of causality
In the year 2000, Judea Pearl published Causality. What controversies surround this work? What are its major criticisms?
Neil G
- 15,219
75
votes
3 answers
What's the difference between feed-forward and recurrent neural networks?
What is the difference between a feed-forward and recurrent neural network?
Why would you use one over the other?
Do other network topologies exist?
Shane
- 12,461
75
votes
7 answers
Which activation function for output layer?
While the choice of activation functions for the hidden layer is quite clear (mostly sigmoid or tanh), I wonder how to decide on the activation function for the output layer. Common choices are linear functions, sigmoid functions and softmax…
Funkwecker
- 3,082