Descriptive statistics summarize features of a sample, such as mean and standard deviations, median and quartiles, the maximum and minimum. With multiple variables, may include correlations and crosstabs. Can include visual displays - boxplots, histograms, scatterplots and so on.

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9 views

Increase ratio pre test and post test

I have a pre test and post test and for each question (15 questions in total) students get 1,2 or zero points. There is an increase in post test but I want to know which score value increased more ...
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30 views

Appropriate Statistical test for Analysis [duplicate]

I have built and tested a computer application, which involved two participant groups (Group-A with existing knowledge of databases and Group-B without knowledge of databases). I was required to ...
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1answer
24 views

Relate $Var(y)$ with $Var(y)_{(i)}$

How can I relate $Var(y)$ with $Var(y)_{(i)}$ where $Var(y)_{(i)}$ is de variance of the data with the ith item removed. It is necesary first relate $\bar{y}$ with $\bar{y}_{(i)}$ and it complicates ...
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1answer
20 views

What's the meaning of 'statistical break'? And how to calculate it?

I am reading a paper named "EPRI-GTC Overhead Electric Transmission Line Siting Methodology", and in this paper the author uses "the first statistical break in its histogram" to determine the corridor ...
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1answer
82 views

Sampling distribution, mean, standard deviation of finite discrete uniform population

Given positive integers $a$ and $b$ ($b \leq a$), where $c$ is the set of all combinations of $a$ digit binary numbers, with $b$ 1's, and where $c_1$ is least significant bit, and $c_a$ is most ...
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39 views

How to describe/define tail of a distribution

I have a histogram showing a distribution with a long tail, and I would like to come up with a definition (in words) for the points fall inside the "tail", not based on quantile or standard deviation, ...
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0answers
27 views

SPSS: descriptives in repeated measures

This is a question that has been bothering me for a long time, and until now I haven't been able to come up with a decent solution. Imagine you do a straightforward repeated measures analysis in SPSS ...
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1answer
71 views

Problem expressing full conditionals

I have this problem, $Y_{i}$~Gamma($\alpha$,$\beta$) 1...N $\alpha$~Exp($\lambda$) $\beta$~Exp($\lambda$) $\lambda$=0.001,Find the full conditionals. I have done the following: ...
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3answers
59 views

What is the term for E[x*y']

I know this is probably a very simple question, but I recall learning that for 2 random vectors, x & y, with mean mx & my, E[(x-mx)(y-my)'] is the covariance & E[xy'] is the correlation ...
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2answers
46 views

Likert Scale 3 2 1 0 1 2 3 possible?

In my questionnaire I want to ask people to score on a dimensional Likert-type scale their attitude toward a specific target group. E.g. People with .... are stupid.... intelligent. I want to use ...
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6 views

making for making dataset for spam classifier [on hold]

I'm trying to make a dataset for spam detection, what is the best automatic selection that I can use for picking up the word that should i count for my spam base ? Thank you
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13 views

Looking for a package to symbolically manipulate statistical expressions

I'm looking for a package that allows to manipulate statistical expressions symbolically, similar to how one can simplify, expand, factor, etc. with Matlab, Mathematica or SAGE. Using rules such as ...
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1answer
45 views

What statistical analysis should I use for my study?

In my psych class we were testing to see if groups of men or groups of women would be more helpful in an emergency situation (we are testing for the bystander effect), and we are testing to see if ...
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15 views

Is it reasonable to utilize z-scores

I have empirical observations to be compared with discrete distributions of random values (generated according to random models). The shape of my random distributions is not normal(according to ...
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0answers
15 views

When is appropriate to combine two treatment groups from one study into a composite whole for a meta-analysis?

The treatment groups I would like to combine appear to be virtually the same, at least by generic label for each group, e.g., groups with the same treatment but implemented at different sites or ...
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0answers
16 views

Comparing two differences in proportions

Based on cross-sectional data from hospitals, I have two 2x2 tables. One 2x2 table is for treatment A. The proportion of males with a binary outcome is 0.2 and females is 0.3, and the difference in ...
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0answers
7 views

What does the standard error of difference 0 mean in form of general statement and then how to proceed further?

I am conducting analysis of data collected from same sample about present state and there expectations on different variables of same service. but t-test cant be conducted on 8 out of 12 variables ...
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1answer
45 views

Calculating standard error after a log-transform

Consider a random set of numbers that are normally distributed: x <- rnorm(n=1000, mean=10) We'd like to know the mean and the standard error on the mean so ...
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0answers
21 views

the approach of performing correlation analysis between categorical and numerical

What are the approaches to perform correlation analysis for the following pairs: ...
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0answers
27 views

Statistical methods in healthcare management [closed]

I am going to contribute to a workshop on "statistical tools for healthcare managers". Any suggestions where I can get some references specific to this area? and data sets?
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17 views

Statistics: Eliminating the effect of one parameter

a quick statistics question. Consider having a conveyor band inside a black box. A test-object is pulled through the black box at different(known) speeds whilst gathering sensor data (temperature ...
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2answers
39 views

Scales of Measurement

when we use the term " scales of measurement", what do we mean by scale by Measurement ? As far i know, measurement denotes "a value" and scale denotes "the unit" of the value. So if i say, ...
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1answer
21 views

How to find three probabilities with two different values or ratings?

I would like to know how to find three probabilities of two values.... Specifically...I want to know the three soccer venues (HOME DRAW AWAY) proabilities with two ratings... Example: I have two ...
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4answers
207 views

Is there a measure of 'evenness' of spread?

I looked up on the web, but couldn't find anything helpful. I'm basically looking for a way to measure how 'evenly' a value is distributed. As in, an 'evenly' distributed distribution like X: and ...
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1answer
29 views

Can I use this equation for prediction?

I've got a question. Below you see a graph which shows the regression equation between construction activities in the private sector (X axis) in £bn and the total amount of all construction activities ...
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0answers
46 views

Is there any use of having dual error bars in bar charts to show both descriptive and inferential statistics?

I would like to display information both about the distribution of the population and the certainty in the measurements in the same plot. Would there be any use of having dual error bars in a barchart ...
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17 views

Decriptive statistics for a large amount of times series

I have 1,000 individual company time series of a variable, say X, observed 500 times (weekly observations). I would like to describe how this variable behaves. A graphic presentation of each time ...
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32 views

Should a BoxCox transformation to normalize the skewness of data be applied to all the predictors?

If there are few predictors that are highly skewed among a larger set of predictors in case of a linear regression problem, should a BoxCox transformation be applied to only these few predictors or ...
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1answer
15 views

Correcting multiple marginals in a subsample of a survey

My question in short: How to assign weights to a subsample of a survey in order to fit multiple features simultaneously to their original marginals? ...and now the details: I have some data set X of ...
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0answers
36 views

Should descriptive statistics on percentages data be weighted?

I'm trying to put together descriptive statistics for a set of differently sized groups of students. For each group of students, let's say I know the # of students who are left handed. I'd like to ...
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1answer
48 views

Linear model decomposition

Is is possible to decompose fitted linear model? What I mean by that: I have parameters of fitted linear model as following: y=2.3a-1.23b+1.65c+1.76d Now I have ...
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0answers
29 views

Using t-test for feature selection after z-scoring data?

Suppose I have a high-dimensional dataset, and a binary classification problem. I want to use the two-sample t-test for feature selection. If the data has been normalized by z-scoring (so it has zero ...
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1answer
19 views

Best statistical method to show different performance week over week

I am trying to get best statical method to show performance of accumulative revenue by customer compare week over week. Currently I have about over 100 customer charts compare by hour from same day ...
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33 views

Statistical nomenclature: what family does “head” and “tail” - in the sense of data runs belong

If I look at mean, variance, skew and kurtosis they are nth moments. If I look at percentiles, quartiles, and medians they are order statistics. Both work together to make a textbook summary. The ...
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2answers
64 views
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22 views

regarding the statistics to test the impact of some subset values on a given variable

For a given variable, there is a set of values. We know that these values can belong to different clusters. For instance, a lot of values center around a small value while other values center around a ...
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1answer
23 views

Matching two power signals for similarity

Below are the images of two signals that i plotted. Both the signals are from fridge belonging to different houses. Visually looking at the plot i can tell that these plots belong to fridge as they ...
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0answers
35 views

questions on characterizing a variable into ordered, categorical or continuous

When building the regression models, some independent variables are of the following type x={1, 2, -100.1, 200.1, 300, 0, 0, 0, 0, 4000} If there exists an ...
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2answers
165 views

What are some good examples of exploratory data analysis today?

Are there some papers published which illustrate EDA used to tackle substantial data problems? I am particularly looking for actual (current) data examples, where plots have been made and statistics ...
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4answers
1k views

How do you interpret the coefficient of variation?

I am trying to understand the Coefficient of Variation. When I try to apply it to the following two samples of data I am unable to understand how to interpret the results. Let's say sample 1 is ${0, ...
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0answers
24 views

What is the variance? [duplicate]

I'm trying to find an answer to this question everywhere, but I'm having a lot of troubles understanding the answers that people are giving; they only confuse me more. I understand that it is a ...
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2answers
42 views

Presenting summary statistics

For a section reporting descriptive statistics should I use the non-transformed variables $x$ or the transformed variables used in the regression analysis (e.g. differenced logs of a variable, $\Delta ...
2
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1answer
20 views

Percentage Beyond a Given Value for Empirically Defined Distribution

It is my understanding that standard deviation does not work well as a measurement for distributions that are heavily skewed. If I have a heavily right-skewed distribution, should I simply use the ...
4
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1answer
25 views

Significance test for longer pronounciation

I have a set of words spoken by a group of native speakers and a group of non-native speakers. In each record I determined the length of the burst (a phonetic term). I believe non-native speakers tend ...
2
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0answers
26 views

comparing two ordinal variables by different groups

I have question. I have two groups, like students above 40 and between 24-40 (variable name :student) Also I have 2 different ordinal variables like (education: primary through Phd) and life ...
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1answer
49 views

When to report proportions and when to report median + IQR for ordinal variable

A colleague brought to my attention documentation for a standardised questionnaire which recommended using the median and interquartile range to describe summary variables created by combining ...
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0answers
43 views

Find interquartile range of these data

Take these data: 5, 8, 9, 14 R says the interquartile range is 3: ...
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1answer
60 views

What is name of this distribution and can we have 68–95–99.7 rule for it?

I have a distribution like this: What is name of this distribution? As you know we have 68–95–99.7 rule in ...
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0answers
11 views

error on truncated rms

I am computing the RMS of a sample to estimate the standar error $\sigma$ of the underlying distribution (for simplicity let say a normal distribution $N[\mu$, $\sigma$]). $ \text{RMS} = \sum_{i=1}^N ...
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1answer
124 views

small sample size, large number of variables (most categorical) - how to proceed?

I would be grateful for general guidance/advice about data analysis with some data that is problematic for me because of the small sample size, and the large number of categorical data. I realize this ...