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Use this tag for any *on-topic* question that (a) involves `R` either as a critical part of the question or expected answer, & (b) is not *just* about how to use `R`.
1
vote
How to predict a univariate time series with Elman neural networks in R
This, at least, is standard in R.
For predicting, there is probably a predict.elman function, to which you will need to feed the values of the explanatory variable x. …
2
votes
Accepted
Using `qnorm` in R
You can either subtract your probability from 1, or use lower.tail=FALSE.
> pp <- 0.2
> qnorm(pp)
[1] -0.8416212
>
> pp <- 0.8
> qnorm(1-pp)
[1] -0.8416212
> qnorm(pp,lower.tail=FALSE)
[1] -0.841621 …
1
vote
Adding a value to each element of a column in R
R vectorizes operations (here: addition) automatically.
> c(1,2,3,4,5)+5
[1] 6 7 8 9 10
(Such questions are better at StackOverflow in the R tag.) …
1
vote
How do I save the vector n into a file called <02_exercises_vector3.txt> such that each lett...
For instance, using cat with the file parameter:
> n <- letters[1:10]
> n
[1] "a" "b" "c" "d" "e" "f" "g" "h" "i" "j"
> cat(n,file="foo.txt",sep="\n")
Look at ?cat.
1
vote
Accepted
R datatable weekday not defined because of singularities
Then R will take care of all dummy encoding automatically. …
1
vote
How to find out the regions a classifier performs well in machine learning?
Take a large amount of testing data, enough to cover a meaningful amount of your IV space.
Apply your classifier to the testing data. Evaluate it, using your favorite error measure.
Use a regression …
3
votes
Identify the original variable used to calculate the dummies
If you can perfectly reconstruct the dummies from a candidate predictor, then the dummies and the predictor carry the same information. If the dummies encode intervals of the predictor (the most commo …
1
vote
How to fit El Nino SST data (as an exogenous data) in ARIMA modeling in R
Yes, you can do that. If you simply feed the data into xreg, then Arima() will fit a regression on your predictor with ARIMA errors. (This is not an ARIMAX model. See here.)
I would recommend that yo …
3
votes
What is the correct way to interpret a $95\%$ confidence interval from the t.test function i...
Your "general understanding" is precisely correct. Each one of your infinitely many experiments will give rise to a separate confidence interval for the parameter of interest (here: the difference in …
1
vote
Accepted
calculate p-values based on an arbitrary distribution
In R, use ecdf():
> xx <- rnorm(100)
> ecdf(xx)(2)
[1] 0.99
To get a p-value, you will need to do some judicious subtraction from one, taking absolute values and/or division by or multiplication by …
1
vote
How to predict values up to two weeks ahead?
Both are available in the forecast package for R.
If you do not expect multiple seasonalities, you could try standard forecasting algorithms, like exponential smoothing (forecast::ets()). … I recommend the excellent free online book Forecasting: Principles and Practice (2nd ed.) by Athanasopoulos & Hyndman, which uses R throughout. …
2
votes
Reporting zero inflated negative binomial regression in APA style
I don't have the APA Publication Manual at hand, but I don't think there is anything specific for a negbin regression in there. I would report it in a similar way to a correlation coefficient. For ins …
5
votes
Accepted
Optimization failure in HoltWinters
The internal optimization in HoltWinters() ran into a numerical problem. That happens. I suggest you try ets() from the forecast package, which will also fit exponential smoothing models, albeit in a …
1
vote
Accepted
Normality of sequence
You are looking at two completely unrelated things. Yes, looking at the normal density evaluated at 1, ..., 100 (and matched for mean and variance) will look normal, because it is. But to assess wheth …
2
votes
Accepted
why does ggplot show outliers but no whiskers?
Note that the middle boxplot does show upper and lower whiskers.
Note that whiskers extend from the box to specific values, namely, for the upper whisker, "the largest value no further than 1.5 * IQR …