# Tagged Questions

Statistical significance refers to the probability that, if, in the population from which this sample were drawn the true effect were 0 (or some hypothesized value) a test statistic as extreme or more extreme than the one gotten in the sample could have occurred.

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### Analyzing Gain Scores and/or correlation in a non-experimental setup

I am a teacher in a language program at a university, and I was interested in investigating whether or not there is a correlation between the number of sessions a student spends in our program and ...
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### How to test differences in means in a population that is not normally distributed, heteroskedastic and differs in variance?

I want to test if the means of two populations are different from each other. There are 12 poulations, all with different sample size, ranging from 48.000 to 300. Here is a 20.000 rows sample. The ...
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### Finding standard error using only mean, min, max and Number? [on hold]

I want to find the standard error and standard deviation Min. = 8 Х104 Max. = 8Х107 - = 9 Х106 n = 36
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### If I'm running a test to determine whether two variables are NOT correlated: what is my hypothesis?

I want to show that two variables are NOT correlated. When I run spearman on it, I get a very large p-value and a correlation of about -0.1. So, I accept the null ...
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### Help Identifying the right statistical hypothesis test

I'm conducting a research which compares the ratio between two categories of words in 2 different text corpuses. Let's say I have corpuses A and B. I created 2 categories of words, Let's call them C ...
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### Can a variable be statistically insignificant but its components be significant?

There is a paper (here) which shows that the beta coefficient of a standardised variable (see equation 3 in the paper), which represents the correlation between the standardised variables, can be ...
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### Election result: How to test for significance?

I guess this is a very basic question, but I find myself unable to find an answer. I want to ask a sample of probands (e.g. N = 467) which one of three presidential candidates they would elect, A, B, ...
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### How to test significant interaction effect

If I have a model, lets say y = a + b1male + b2large + b3medium + b4malelarge + b5malemedium where male is dummy coded 1 for male and 0 for female and large and female are dummies (also 0,1 coded) for ...
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### Which statistical test to use to determine if some values Ys influence X?

I have a NetLogo simulation which has a parameter to determine how to calculate some distance. This parameter can take one of three values for each simulation run. The experiment consists of running ...
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### P-value word problem question

I'm having trouble understanding this question from my statistics class: I handed out a flyer about a rock show to 20 people who, at that time, did not plan on attending the show. My hypothesis is ...
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### correlation between score and variable across different methods

I am using three different Machine learning methods to segment images, with a score for each image. I would like to show that there is a relationship between the score and the image, rather than the ...
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### Logistic regression: Is there a significant difference for probability p between groups of Bernoulli random variables?

Let $S_{I+1} = \{1,2,\cdots,I\}$. And assume that there are exactly $J$ observations $(x_j,s_j) \in \mathbb{R} \times S_{I+1}$ for each integer $j$ such that $1 \leq j \leq J$. For each $i \in S_{I+1}$...
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### statistical test for analyzing survey data

One question of my survey (n=468) was to indicate on a scale from 1 to 5 how well they know our government. My hypothesis is that women know our government better than men. What statistical test do I ...
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### Pairwise significance test with different variances within sample

I'm trying to test the significance of changes in the sales volume from one year to another. For each store I know the sales in 2014 and 2015 each day and would like to do a pairwise significance ...
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### Are my regression lines from the same population? [duplicate]

I have two sets of data looking at weight change over time. Subjects within each data sets have weights at multiple time points. The first is a small set of data I used to determine an equation to ...
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### Comparing the degree of similarity between groups

I have three groups A, B and C and I want to prove that similarity between group B and group A is significantly higher than between group B and group C. How to prove it? Simple example: I have ...
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### Why are confidence intervals and p-values not reported as default for penalized regression coefficients

I have been using the R package glmnet to do penalized regression. As part of this the package does not produce confidence intervals or p-values with regression ...
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### Mann-Kendall trend test of time series in Spss [closed]

My question is about Mann-Kendall test. I have the need to evaluate data of precipitation to see if the amount of precipitation during last 50 years in my study site is following a trend or not and if ...
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### How deeply to probe a large pool of data for statistically representative sample?

I have a basic stats questions, just trying to find pointers for a set of calculations the details of which might be too complex to flesh out here. Imagine you have a population of 10^10 and are ...
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### Is logistic regression a valid way of analyzing A/B testing results?

I'm very new to the idea of A/B testing and I want to see if my train of thought here makes sense. Suppose that I run an experiment with two designs. I get two sets of resulting data, one for each ...
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### Is dependency created when adding one variable which is the difference of two existing variables to a regression model?

I have two variables $x_1$ and $x_2$ in linear regression. I would like to see if the distance between $x_1-x_2$ is significant. So I want to add one more variable $x_3$, which is equal to $x_1-x_2$. ...
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### The significance of existing variables decreases after adding additional variables in regression [duplicate]

I build a simple linear regression, $y=w_0+w_1x_1$. I find the coefficient of $x_1$ is significant. Then I add $x_2$. It shows that the coefficients of both $x_1$ and $x_2$ are NOT significant any ...
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### Prediction Algorithms in Statistics

Here it is what I'm looking for: Having a random variable, with an unknown distribution of its values, is there any smart algorithm that can predict the next value of the variable based on n samples ...
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### Statistics on Proportional Values (Percents)

What kind of statistics should I use on my values which have a proportional (percent value). I have 3 treatment groups, which 3 values each (n), which I need to see if the means differ. The same ...
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### p-value of logrank test with three groups

I faced with the following situation. There are 3 groups in my data and I am to compare pairwise these groups and obtain logrank p-value. If I am to compare say 1 and 3 groups should I remove the 2nd ...
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### Comparing a single point in two time series

I have two time series of males and females traveling from point A in between 1979 to 2001. The question is, is there a significant difference in the number of male and female travelers in year, say, ...
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### Test for difference of spatial/temporal distribution

I have the data of the average hourly consumption of electric power in 50 districst of a city, for the days of 2 months: ...
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### Inconsistent pattern between mixed regression and data plot

I built a mixed linear regression model which includes a dependent variable 'dv', independent variable 'v1' & 'v2', and subject ID 'subject'. The R syntax is shown below: output <-lmer(dv ~ ...
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### How do I work out wether a cohens d effect size is significant?

I'm currently doing a meta analysis where I have to convert the results to a cohens d. I obviously have different samples/ tests including paired samples and odds ratio for example. I'm wanting to ...
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### How to test whether two coin replicates are both biased in one direction?

Assume we have two coins replicates, which are produced in the same pipeline. To test whether the coins replicates are both biased in one direction (e.g. the probability of head > 0.5), we did flip ...
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### calculating weighted CIs and interpretation

I have a weighted mean and I would like to calculate a weighted confidence interval and had a couple questions about interpretation. If one calculates the standard error of the weighted mean ...
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### How to validate simulation result with real data

I have made a computer simulation, which is a model of a machine process step in a real factory. This factory keeps track of certain KPIs (key performance indicators), like utilization (% of time in ...
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### How to test the significance of long term effect coefficient

I have a time-series model like this: $y_t=\alpha+\beta_0 y_{t-1} + β_1 r_{t-1} + x_t' β_2 + \epsilon_t$ in order to get the long term effect, I use $β_1^*=\frac{β_1}{1-β_0}$ to measure, this is ...
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### What is the right usage in Fisher test in R

So I have data in form (in real data I have more rows, of course so this is just a sample) ...
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### significance between comparisions

I hope this is the right forum for this kind of question (otherwise please point me to the right one). We are working on a RNA-Seq data set (10 biological replica for three conditions). We have ...
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### Statistically significance test to compare a ML classifier to a group of experts?

I am working on a medical data set of 60 test samples and I have the decisions of 45 medical experts for them over 5 diagnostic classes. How should I do hypothesis testing to show that the classifier ...
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### Can I use a paired t-test on data that are averages?

I am comparing 15 pairs of averages paired by two categories with a paired t test. The samples used to determine the averages in each pair are not equal within any single pair of data. For example, if ...
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### Statistical Significance of dependent variables (Distributions)

I'm computing the statistical significance two classifiers applied on the same dataset using 10-fold cross validation over 30 runs. Performance is computed in terms of precision (P), recall (R) and ...
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### Silhouette score significance: what is a significant increase in silhouette score?

I'm aware a silhouette score ranges from -1 to 1. But what can be considered a significant increase? 0.1 to 0.2 (because 100%) or 0.5 to 0.6? Obviously higher is better, but is there some measure of ...
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### A/B Test: Determine if a Lift in Measured Sales is Significant

I am no stats expert so any assistance will be greatly appreciated. I’m working on a post-campaign analysis to determine if any measured sales lift (sales lift per audience) is significant between ...
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### Is Root Mean Squared Error computed according to model with all variables or only significant ones?

I made VAR model where there are some statistically insignificant variables. I ran forecast and I wanted to compute Root Mean Square Error. I tought that RMSE is computed according to model with only ...
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### How to test if two sets of vectors are statistically different from each other

I have a set of 2-dimensional vector observations (like to wind vectors), and I have separated them into subsamples based on whether an event that is independent of the observations occurred or not. ...
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### a/b testing revenue increases

I have 4 geo specific groups. In each of the first three groups, we spent different levels of money in a marketing channel and curtailed all spend in the last. The groups have been designed to be ...
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### Testing for a statistically significant difference across multiple categories with ordinal data

I have ordinal data from a single reviewer who ranked the quality (and other factors) of 66 reports. 19 of these reports were about mining, 10 about Waste, 10 about Infrastructure, 9 about transport ...
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How would you interpret the outcomes if your predictor significantly predict the outcome variable (p value = .013) only in the adjusted model and not the unadjusted one (p value = .542)? Could you ...
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### How to test for group differences in poisson distributed variables with unequal length?

I would like to test group differences in poisson distributed variables. However, I'm struggle to find appropriate approach(using R), which encounters unequal ...
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### Is this data's mean significantly different from zero?

I need to make a statement regarding whether the mean of this data is significantly different from zero. The data can not be described by a normal distribution. The population's size is 27, mean is -...
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### Statistical tests to data organized by weekdays

I have data where there are numeric values (can be 0 also) for corresponding weekdays (1=monday, 2=tuesday, 7=sunday etc). I want to find out if my values (say, for temperature for example) depends on ...