# Questions tagged [rule-of-thumb]

Advises on statistical analysis that are often useful in practice (but are not always guaranteed to work).

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### How small is too small to fit a reasonable long memory model?

When looking at papers about long memory they tend to analyze data sets whose length is in the thousands, see http://www.math.canterbury.ac.nz/~m.reale/pub/Reaetal2011.pdf for an example. My question ...
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### How should I treat categorical variables for the purpose of the “One in 10 rule”?

Hope a basic question like this is alright! To avoid overfitting, we try to maintain enough cases for the least common event per explanatory variable; people usually recommend at least 10. How should ...
356 views

### Equality of variances based on Rule of Thumb (for very small groups)

I have three groups with very small sample sizes (6 obs per each group). In order to use ANOVA I just want to make sure that the equality of variances is satisfied, as Levene's test does not have ...
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### How does one formalize a prior probability distribution? Are there rules of thumb or tips one should use?

While I like to think I have good grasp of the concept of prior information in Bayesian statistical analysis and decision making, I often have trouble wrapping my head around its application. I have ...
751 views

### Rule of thumb for the number of significant digits to report

What is a good rule of thumb for the number of significant digits to report? Preferably, the rule of thumb is given in a citable publication. I am particularly interested in a rule that does not ...
2k views

### How to tell a coefficient of variation (C.V.) is high?

I have a group of data series which contain hundreds of values. I've calculated the C.V.s of these data series, but I don't know how I can recognise if they are high or low according to the C.V. ...
859 views

### Rule of thumb for using logarithmic scale

When I am given a variable, I usually decide whether to take its logarithm based on gut feeling. Usually I base it on its distribution - if it has long tail (like: salaries, GDP, ...) I use logarithms....
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### How do “stacked” repeated samples influence our rules of thumb for minimum samples size in regression?

A professor in one of my graduate statistics courses once said, when briefly reviewing simple linear regression: "I would never EVER fit a line to fewer than 8-10 data points, it would make me feel......
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### Optimal number of bins in histogram by the Freedman–Diaconis rule: difference between theoretical rate and actual number

Wikipedia reports that under the Freedman and Diaconis rule, the optimal number of bins in an histogram, $k$ should grow as $$k\sim n^{1/3}$$ where $n$ is the sample size. However, If you look at ...
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### How strongly supported is a conclusion drawn from the correlation of 10 observations?

The Spearman’s rank correlation coefficient calculated for these observations is 0.826 (p<0.005). Is there something like a "rule of thumb" minimum number of observations?
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### “When to use boxplot and when barplot” rules (of thumb?)

Both box-and-whisker plot and bar chart are appropriate graphics for ANOVA according to The R Book (Crawley, 2013), but which is more appropriate? I suppose it depends on situation... can anybody help ...
720 views

### Is there a simple method to calculate the minimum number of datalines needed for a machine learning algorithm with x variables?

Here is the problem: I am making a machine learning algorithm that takes the inputs and outputs of some software I've written, and I don't know how many datalines to produce to get results that are a '...
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### Rule of thumb when drawing N samples from a discrete distribution with N possible values with replacement

I'm looking for an explanation and possibly the name of a rule of thumb: When drawing N samples with replacement from a discrete uniform distribution of N values, it is very likely that: 1/3 of the ...
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### Minimum items for questionnaire

Is there a minimum item for questionnaire? Some researchers said that the total items for teenagers ranging from 80-110 items
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### Min-max vs. standard deviation when plotting error bars

I am running some experiments in which I plot the values of some variable y (averaged over 4 runs) against some independent variable x. I also compare the effect of z. In other words: horizontal axis:...
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### Histogram with uniform vs non-uniform Bins

This question describes the basic difference between a uniform and a nonuniform histogram. And this question discusses the rule of thumb for picking the number of bins of a uniform histogram that ...
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### Is Rule of Three inappropriate in some cases?

I'm building binomial proportion confidence intervals for a patient dataset containing the frequency of home nursing visits during the week prior to hospital admission. The freq. of home visit ...
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### Rule of thumb - number of predictors - Poisson regression rates

I am interested in estimating a Poisson regression for mortality rates, with number of deaths as the dependent variable and log(population size) as the offset. I have 50 observations (states). I am ...
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### Rules of Thumb to choose an initial number of class intervals and refine that choice (potentially automatically)

I was wondering if there are established rules of thumb (or algorithms) that, given a set of observations can help: choose an initial number of class intervals. refine that choice to a better number. ...
6k views

### How to decide which decision tree classifier to use?

I am confused about which decision tree algorithm in weka to use for my application. I have 5 real input variables and 2 classes. In various online tutorials J48 (C 4.5) seems to be the algorithm of ...
2k views

### Basic easy rules for statistics

In a binomial experiment, if we observe $x=0$ positive individual among $n$ individuals, then the proportion of positive individuals is significantly lower than $3/n$ with a type 1 error less than and ...
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### Effect size interpretation

If r between X and Y is 0.74, then r-squared is 55%. According to many 'rules of thumb' and others, the effect size (in this case r) is considered 'moderate' or 'medium'. As such, only 55% of the ...
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### Good online resource with tips on graphing association between two numeric variables under various conditions

Context: Over the while I've acquired a set of heuristics on how to effectively plot the association between two numeric variables. I imagine most people who work with data would have a similar set ...
741 views

### $L_1$ or $L_.5$ metrics for clustering?

Does anyone use the $L_1$ or $L_.5$ metrics for clustering, rather than $L_2$ ? Aggarwal et al., On the surprising behavior of distance metrics in high dimensional space said (in 2001) that $L_1$ ...
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### Rules of thumb for minimum sample size for multiple regression

Within the context of a research proposal in the social sciences, I was asked the following question: I have always gone by 100 + m (where m is the number of predictors) when determining ...
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### Sample size required to determine which of a set of advertisements has the highest click through rate

I am a software designer by trade and I am working on a project for a client, and I would like to make sure that my analysis is statistically sound. Consider the following: We have n advertisements (...
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### When to use Equal-Frequency-Histograms

... instead of e.g. the popular Equal-Width-Histograms. Additional question: What is a good/robust rule of the thumb to calculate the number of bins for equal frequency histograms (like the ...
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### MANOVA and correlations between dependent variables: how strong is too strong?

The dependent variables in a MANOVA should not be "too strongly correlated". But how strong a correlation is too strong? It would be interesting to get people's opinions on this issue. For instance, ...
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### Rules of thumb for “modern” statistics

I like G van Belle's book on Statistical Rules of Thumb, and to a lesser extent Common Errors in Statistics (and How to Avoid Them) from Phillip I Good and James W. Hardin. They address common ...