A brief numerical description of a set of data.

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2
votes
1answer
72 views

Is it Poisson distributed, and if so, what's its meaning?

I've collected data from my website. The website is about cars. The data are about user reviews and the cars. what we see in the graphs is the probability of some car type (Ford Focus 2008) to have X ...
3
votes
0answers
32 views

Weighting on tables

I have a question about terminology. Suppose I have data categorized by three factors A, B, and C, with cell means $\bar{y}_{ijk}$ and cell frequencies $n_{ijk}$, where $i$, $j$, and $k$ index A, B, ...
3
votes
0answers
100 views

Better estimator of expected sum than mean

I am trying to find the optimal estimator for the maximal expected $\Sigma X_i$ where $X_i$ is sampled from an unknown distribution which is chosen to be maximal. To clarify and simplify, there are ...
0
votes
1answer
39 views

What is the z-value of glm model parameters?

I know what the z-value of a single observation is, that is explained in Wikipedia. But what is the z-value of a parameter in a glm model?
0
votes
1answer
31 views

Comparing salaries in different countries

I have a number of salary figures for roles that I want to compare across various countries. Obviously each country has their own currency and living costs. A simple way of comparing would be to use ...
0
votes
0answers
16 views

Variation within and between groups

So in my data, I have parameters(~800) and each parameter has 14 different groups. I individually know the mean and standard deviation within each group for each parameter. The data within each group ...
1
vote
0answers
26 views

Variance of sample mean in a binomial distribution

I'm trying to derive that the variance of phat = pq/n. I'm unfortunately not getting that. Please tell me where I'm going wrong... ...
1
vote
0answers
30 views

Computation of parameters of truncated normal distribution

I have a numeric data sample with mean $\mu$ and standard deviation $\sigma$. I believe that this data has a normal distribution truncated to $[0,1]$. Is there a reasonably simple formula for ...
0
votes
0answers
30 views

selecting the bins for extremely skewed data

I have a data that exhibits nearly a power law distribution, and I want to know a good binning technique to summarize the statistics. For example consider the following data: $$ \begin{array}{rr} ...
4
votes
2answers
58 views

Descriptive statistics show more than 100%

I have race as a variable in my model and my measurement reflects the executives' race in the company's management (score 1 if any specific race is in the management). The problem is that managements ...
0
votes
0answers
15 views

What statistical model can be used to find how following variables relate?

I want to find the relationship between a disease incidence in a region and a number of other environmental factors such as temperature, elevation etc. I have tables containing this data for a ...
0
votes
1answer
31 views

Bootstrap hypothesis testing with small sample sizes

I have 2 campaigns (a control and a test campaign), the data are like this: ...
0
votes
0answers
7 views

Probability of a sale in a given month based on past activity including order frequency

The sales history for customer A looks like this: Jan : $500 (4 sales) Feb : $200 (2 sales) Mar : $0 (0 sales) etc.. I want to know: The probability of ...
0
votes
2answers
63 views

Can I use Empirical Cumulative Distribution Function to derive standardized values of various data sets?

I have an idea to use ECDF conversion of data to their uniform distribution of equal sample sizes. So, for say 1000 pieces of data, each value should more or less correlate with a .1% representative ...
0
votes
0answers
26 views

Reference to the formula for sample variance of combined samples

One can prove it by a straightforward computation that the sample variance of two samples combined is $\sigma^2=\frac{N_1-1}{N-1}\sigma_1^2+\frac{N_1}{N-1}\mu_1^2+ ...
3
votes
2answers
47 views

Can you compare two groups with only partial summary information?

I have to group $A$ ($\bar X_1 =20, N_1=10$) and group $B$ ($\bar X_2 = 25, N_2=15$). Is there a way I can compare these two groups and get some statistical significance? I was thinking about using ...
0
votes
0answers
27 views

Is there any MOOCS on statistical analysis of Applied behavioral economics?

I couldn't find a single MOOCs on Applied behavioral economics and statistics, on how can we used statistical analysis in behavioral economics. If someone can point me in the right direction, it would ...
0
votes
0answers
34 views

Confused about the basic maths in Incremental/Uplift modelling

I have recently gotten to study Incremental modelling, which is used in Marketing to study the incremental impact of a certain action on a treatment group against a control group. However, I am very ...
0
votes
0answers
24 views

Syntax for means and standard deviation on repeated measures GLM in spss?

This may be a silly question, but when running a repeated measure GLM in SPSS, and entering syntax for means tables (/EMMEANS), is there any way to get that table to show not just the standard error, ...
0
votes
2answers
27 views

Dependent t-test - multiple readings

Let's suppose that I'd like to apply dependent t-test to assess if there is a significant difference in the value of the dependent variable between a group of subjects $X_{1}$ and a related group of ...
1
vote
0answers
13 views

What is the best analysis to perform on brute force tests?

Basically, I have run a network simulation for video streaming a number of times. I have assigned weights to particular performance metrics of the network measuring their performance each time. ...
0
votes
1answer
44 views

Dispersion measure - probability density function

I am wondering whether someone has a tip on this potentially very basic question. i have done some grid-based bayesian analysis and ended up with a non-standard discrete posterior density function ...
8
votes
1answer
672 views

How did Karl Pearson come up with the chi-squared statistic?

How did Pearson come up with the following Pearson chi-squared statistics in 1900? $$ K = \sum \frac{(O_{ij} -E_{ij})^2}{E_{ij}} $$ that $$ K \sim \chi^2 $$ Did he have chi-squared in mind and ...
0
votes
0answers
11 views

How to calculate summary statistics for nested factors?

I have a data set where I have two levels of within variables. I have a set of Scenarios and each scenario has a set of Trials, ...
1
vote
0answers
59 views

Feature extraction for customer churn data

I have a customer churn data, and would be implementing algorithms (decision tree, logistic regression, segment analysis). I have doubt on feature extraction procedure though. The training sample has ...
0
votes
0answers
40 views

ANOVA or any other tests for differences in R

I have a timecourse dataset consisting of 3 groups of patients as follows: Group1: control Group2: Medication A to reduce pain after a medical procedure Group3: Medication B to reduce pain after a ...
0
votes
0answers
33 views

What kind of statistic analysis fits in my data?

I am not mathematician, but I want to do a small statistic analysis in my data. I have data from basketball matches in the following format: ...
0
votes
0answers
89 views

One-way ANOVA from summary data in R

I want to statistically compare the mean values from eight different groups. I do not have the raw data, but have the sample size, mean and associated standard deviation and standard error. I was ...
0
votes
1answer
31 views

How can you define below average, average and above average according to percentile rank?

A particular school evaluation lists abilities by percentile rank against the abilities of a population, and each ranking/ability is then given a group ranking of "Below Average", "Average", or ...
2
votes
1answer
42 views

Five-number summary and mean

Why was not mean included in the five-number summary, when it was first conceived? What was the motivation of choosing sample minimum & maximum, lower & upper quartile and median?
2
votes
1answer
30 views

What quantifies a stable parameter?

I'm optimizing 5 parameters for an option pricing model. Now I want to asses whether these parameters are stable over time (i.e., a year). For this I create about 12 subsamples and estimate the ...
1
vote
1answer
45 views

Estimating an overall summary statistic (mean) for a value reported by ten published studies

Background I am writing a systematic review and meta-analysis of the association of exposure to X with the outcome Y. I have identified ten studies that report on this subject. This will be a ...
0
votes
0answers
14 views

Statistical tests to check quality of data before learning model

I have collected some gene expression data and I want to learn a Bayesian network out of it. Before that, I want to do some statistical analysis to test the quality of my data. Now I want to know ...
1
vote
3answers
30 views

Standard deviation of the mean? [duplicate]

I don't think I understand how you can have a standard deviation of a mean σx̅. x̅ is all the sum of all values divided by the sample size n. It's a single value. How can there be a standard ...
0
votes
1answer
35 views

How to determine probability of score when selecting from pool of values?

The question seems simple but I just can't solve it. I have twelve test scores and three are to be picked at random to determine the overall test grade. How can I calculate the probability of my ...
1
vote
2answers
107 views

Homoscedastic and heteroscedastic data and regression models

How to understand the homoscedasticity and heteroscedasticity in context of regression models? Is there a way to check these properties in R?
0
votes
0answers
12 views

What is the individual's ID in the 1994 Peru LSMS dataset?

I had a quick question about the Peru LSMS from 1994 (http://microdata.worldbank.org/index.php/catalog/617). The LSMS is split up into several dozen files, all of which contain different pieces of ...
2
votes
0answers
83 views

I have a problem with bayes and train lines

I have this problem which I can't fully understand it: Assume you have entered in a foreign city of unknown size. At entrance you see a tramcar with number $100$. Let us assume that the tramcar ...
5
votes
0answers
143 views

If the distribution is bimodal, does p-value mean anything?

P-value is defined the probability of obtaining a test-statistic at least as extreme as what is observed, assuming null-hypothesis is true. In other words, $$P( X \ge t | H_0 )$$ But what if the ...
3
votes
1answer
38 views

What is the interval that relates to the mean as the equal tailed interval relates to the median and the highest density interval relates to the mode?

When summarizing a one dimensional continuous distribution (e.g. a posterior distribution) it is common to use either an equal tailed interval (aka quantile-based) or a highest density interval. The ...
0
votes
0answers
39 views

Regression Puzzle GLS var/covar matrix of B given summary statistics

There is a problem posted back in 2009 that I found that has me puzzled. I believe the estimates are from a generalized linear regression because after some thought it seems $X'X$ is impossible to ...
0
votes
0answers
39 views

Cox regression with interaction giving NA values, how to interpret? + Choosing covariates based on p-values

I am working with a dataset with 12 covariates(categorical). The covariates have different Levels, some are from 0-5, and one has as much as 0-11 categories. I started with a univariate analysis to ...
8
votes
2answers
642 views

Is variation the same as variance?

This is my first question on Cross Validated here, so please help me out even if it seems trivial :-) First of all, the question might be an outcome of language differences or perhaps me having real ...
1
vote
0answers
26 views

Limitations of using interpolated data

I have a data set that is composed of point locations in a landscape, lets call this dataset X. Some of the points in data set X need to be grouped together because they "function" together as a ...
4
votes
2answers
164 views

Does the slope of a regression between observed and predicted values always equal the $R^2$ of the original model?

As the title to my question says, I am confused as to when the $R^2$ of a model fit does not equal the slope of the regression between observed and predicted values. I am trying to present model ...
-4
votes
3answers
96 views

Null Hypothesis [closed]

A survey found that 70% of college professors believe that their online education courses are as good as or superior to courses that use traditional face-to face instruction. What is the null ...
2
votes
0answers
48 views

Markov chain and process

This is not homework. Just practicing for an upcoming exam. Question is taken from a web pdf : http://www.dartmouth.edu/~chance/teaching_aids/books_articles/probability_book/Chapter11.pdf Consider ...
0
votes
0answers
45 views

How to measure the randomness of a time series?

I have at least two time series. How can I measure which one of them is more random than the others? I am also interested in monitoring the changes in the amount of randomness over time for an ...
0
votes
0answers
17 views

variance, standard deviation and standard error [duplicate]

When describing the variance of a sample data set, we can use variance and standard deviation. ...
0
votes
0answers
83 views

Cumulative standard deviation calculation

I have a calculated daily survival probability, and associated SE. From this I can obtain the standard deviation. I have to report the cumulative survival over a specific period. So for example, for a ...