# Tagged Questions

This tag indicates questions about definitions of statistical terms. Use a more general tag [terminology] for questions on statistical parlance that are not specifically about definitions.

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### Do convolutional neural networks flip the kernel?

After reading various examples of CNNs it doesn't look like the kernel used for convolution is flipped. Can anybody explain why?
293 views

### Wikipedia entry on likelihood seems ambiguous

I have a simple question regarding "conditional probability" and "Likelihood". (I have already surveyed this question here but to no avail.) It starts from the Wikipedia page on likelihood. They say ...
38 views

### Is there an accepted definition for “P for trend” or “P-trend” [duplicate]

So is "P for trend" the same in principle as a common-or-garden P-value, but in a specific application i.e. odds ratios? And can P-value, P for trend, and P-trend be regarded as interchangeable ...
21 views

### Is there such thing called sum of absolute sum?

Sum of absolute difference (SAD) is common in image processing as a measure of similarity. Is there such thing called sum of absolute sum in image processing or other field? Does it have any ...
19 views

### Conditioning within definition explanation

I have a doubt on the meaning of a conditioning within a definition. In a book I've found the following definition of upper tolerance limit: $P(P(X<\bar X+kS|\bar X, S)>p)=1-\alpha$ where $X$ ...
37 views

### Notion of “the same” distribution in definitions of “iid” and “exchangable”

Schervish's (1995) Theory of Statistics defines exchangeability like this (p. 7): A finite set $X_1, …, X_n$ of random quantities is said to be exchangeable if every permutation of $(X_1, …, X_n)$ ...
15 views

### Time series with slightly unequal intervals

I'm very new to statistics, and I have a problem that may or may not exactly be considered a time series analysis problem. I have a large set of vehicle location measurements (x0, y0)...(xt, yt) taken ...
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171 views

### Does “improper” posterior or prior refer to a density function that does not integrate to 1 or to one that does not integrate to a finite value?

I am a bit confused about improper priors and posteriors. I have seen references that classify a prior or posterior probability density function as "improper" if the integral over infinite support ...
130 views

### do(x) operator meaning?

I have seen the $do(x)$ operator everywhere in some literature review I am doing on Causality (see, for instance this wikipedia entry). However, I cannot find a formal and general definition of this ...
562 views

### Is there a formula for computing median?

Is there an equivalent of the mean formula: $$\mathrm{mean} = \cfrac{1}{N} \sum_{i=1}^{N} X_i$$ for median?
821 views

### What's in a name: hyperparameters

So in a normal distribution, we have two parameters: mean $\mu$ and variance $\sigma^2$. In the book Pattern Recognition and Machine Learning, there suddenly appears a hyperparameter $\lambda$ in the ...
192 views

### What is an isotropic (spherical) covariance matrix?

Could somebody explain to me in simple terms what an isotropic covariance matrix is? I can't find anything online.
35 views

### Difference between Discrimination, Calibration, Accuracy and Precision

I have trouble understanding these terms: a.) Discrimination. b.) Calibration. c.) Accuracy. d.) Precision. I really get confused with the books I am reading, ...
79 views

### Do we say that the $y_i$'s are i.i.d. if $n_iy_i \sim \text{Binomial}(n_i, \theta)$?

If $y_i$'s are independent and for given $n_i$, $$n_iy_i \sim \text{Binomial}(n_i, \theta)$$ Could we say that $y_i$'s are i.i.d.? If not, then what's the proper way to address such problems?
18 views

### What are dynamical process?

Can someone explain to me what are Dynamical processes? It would be helpful if someone can also give me an example/s (if possible, in context of atmospheric or environmental processes) regarding this.
39 views

### Layman's definition of high-dimensional data

I'm a statistician writing a research proposal to be read by non-statisticians. This will mostly include mathematicians, computer scientists, and engineers, but may also include those in humanities. ...
12k views

### What is a data scientist?

Having recently graduated from my PhD program in statistics, I had for the last couple of months began searching for work in the field of statistics. Almost every company I considered had a job ...
16 views

### remove the mean over multiple measurements

I have a set of multiple measurements for each subject (i.e. each subject is assessed several days). For each set of measurements (several days of the same subject) I am calculating the mean value of ...
35 views

### Ground truth Vs. Baseline [closed]

I was wondering what the difference between ground truth and baseline is? Is it necessary that a system should always be tested ...
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### What's a linear aggregate?

A paper I'm reading (Davis-Stober et al, 2014) contains the following statement: A crowd is wise if a linear aggregate, for example a mean, of its members’ judgments is closer to the target ...
354 views

### Difference between within-group and between-group covariance matrices in linear discriminant analysis

Could someone explain to me the difference between within-group covariance matrix and between-group covariance matrix in the context of linear discriminant analysis?
261 views

### What is the definition of “rare events”? and when it matters for significance testing of differences in a control-case study?

What is the formal definition of "rare events"? and when it matters for significance testing of differences in a control-case study?
818 views

### Ground-truth definition

I have found two meanings of how "ground truth" is being used in machine learning: Something to be assumed true Something previously validated as true Although similar in detail the two can differ....
90 views

### Computing required sample size for paired t-test

I have some paired t-test data (40 pairs) and I would like to use these data to estimate the sample size required if I were to conduct the study again with a new set of requirements. I'm using ...