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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representative samples formula [on hold]

I have just started working in quality management and I need to work out a representative sample of a given population of inputs needed for our production to assess them i.e if the bottles we get ...
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1answer
22 views

Why pnorm function and sum of dnorm function differs for same input?

Data is height of men in 'inches'. Mean is 70. SD is 3.3 I wanted to compute the probability of men whose height is in between 69 inches and 74 inches. The following methods gave me different ...
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3answers
23 views

Non-normal univariate distribution — how to define “low” to “high” subsets of values?

Sorry for the dumb question: it's been a million years since I took basic stats. I have a set of 48, non-normally distributed values ranging from 1 to 100. I'd like to be able to apply a (valid) ...
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18 views

suitable statistics to replace box plot [on hold]

I am applying few classification methods on a set of images. Currently, I have experimental results in box-plots and want some statistical method to report them in my dissertation. Problem ...
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20 views

Issues with derivative of a copula density

Suppose I have a bivariate copula density with marginals $F(X)$ ($F(X)$ is normal with parameters $\mu_1$, $\sigma_1^2$) and $G(Y)$ ($G(Y)$ is normal with parameters $\mu_2$ and $\sigma_2^2$). I want ...
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34 views

Estimating probability distribution function of data stream

Although a similar question exists, I couldn't find my answer. I'm not a statistician hence please neglect if some terminologies aren't correct and let me know if I am interpreting something wrong. ...
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0answers
16 views

Can you calculate descriptive statistics (SD, SE particularly) from percentages and ratios?

I'm a cell biologist and a lot of my data is expressed as a fraction (percentage) of the total number of cells in a single experiment in a number of separate categories (generally 5 or so). The number ...
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1answer
27 views

What's my population? Is this Descriptive or Inferential?

I have a list of employees at a company. I want to show some comparison of some demographics (say, %female) of those who have left the company and those who have stayed with the company. However, I ...
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1answer
218 views

Is the following dataset possible?

"Is it possible to create a data set where $\bar{x}=30.0$, range $R=10$ (meaning the max-min=10), and variance $s^2=40.0$?" I feel sort of dumb asking this question, but I'm not quite sure I'm on the ...
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34 views

Efficient statistical test to compare two multivariate distributions

I am looking for a test to assert the "equality" of two multivariate discrete distributions, $\mathbf{A}=\{A_1,\dots,A_k\}$ and $\mathbf{B}=\{B_1,\dots,B_k\}$ for which I do observe two samples ...
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13 views

Forecasting Prediction Accuracy

Out of 4 error paramters which one is best for evaluating prediction accuracy? Average error Mean absolute error Mean squared error Mean absolute % error why?
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20 views

What is the best way to group countries for graphing world crime statistics?

I am currently working on a project where I have chosen to analyse the frequency of terrorist attacks and their impacts using the global terrorism database (dataset available here: ...
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15 views

Chi-square and subsequent comparisons

I have the following dataset and would like to find out firstly if I'm using the correct tests. The data are hospital admissions data for cause X and admissions data for all admissions. If an ...
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1answer
21 views

Meaning of a higher out-of-sample $R^2$ but also a higher MSPE

I am comparing several forecasting methods using the out-of-sample $R^2$ and MSPE. Now I have encountered situations in which the $R^2$ of a certain method is higher than that of the other, but the ...
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18 views

How to determine the number of employees in a business when sources are inconsistent?

I am analyzing a business survey data. I am interested in the total number of employees of each firm. Specifically, I am interested in: The total number of employees in a specific city, and The ...
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41 views

How to show whether a hypothesis is true or not

I have the following hypothesis: "The higher the number of translation-stable words between a pair of countries, the higher the correlation between the happiness scores of their words". note: ...
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1answer
45 views

Can a truly randomized procedure (e.g. random treatment allocation) result in unbalanced distributions?

Thousands of randomized trials are ongoing or in the planning. These trials rely on randomization procedures (e.g. patients being randomized to either placebo or active drugs) to yield two balanced ...
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3answers
643 views

Do descriptive statistics have p-values?

I'm being asked to find the p-values for descriptive statistics. However, it's my understanding that p-values are for test statistics. If I'm not mistaken, a p-value is the probability of observing a ...
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1answer
22 views

Using counts of a continuous random variable to establish an unknown probability density function

The precision of a given measuring device defines a window over the probability density function of whatever is being measured. For instance, if a measuring tape is precise to 0.1 inches, then the ...
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1answer
46 views

Determining continuous vs discrete data sets?

When I collect data for my work, I get a set like the following: [ 133, 183, 185.16, 188, 143, 128, 135.5, 100.55, 117.96, 95.5 ] These points are part of a ...
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1answer
41 views

Results of 2-sample t-test does not seem intuitive; wrong procedure?

I have data shown below, with a response variable tabulated by hour (x-axis) as well as numerous other factors: larger chart available here I want to see if the colored points (red, light and dark ...
2
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1answer
21 views

How to compare age across multiple groups?

I have age data on 5 groups, and I would like to compare if one group is significantly older or younger than another. When comparing 2 groups, I can use a 2-sample t-test, but when comparing across ...
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1answer
47 views

How to rank monthly data, using both trends and averages

I have a very large data set containing the daily searches for some Wikipedia entries. I am using the number of searches as proxy of popularity and want to rank the entries. Lets say I have entities ...
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12 views

Using predictive algorithms for descriptive purposes? Correct? Any resources?

Newbie here. I've been learning lots of predictive modeling with R/python using the well-known algorithms: decision trees, random forests, SVM, logistic/linear regression, k-Means, k-NN. But I'm new ...
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2answers
33 views

Compare lists of genes

I have two lists of differentially expressed genes: the list 1 was derived from the universe A of total genes while the list 2 was derived from the universe B of total genes. A number of genes is in ...
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1answer
33 views

Describing trend magnitude or detecting trends

I have time series data. One observation per time period, about 10 observations or so. When describing the data (I am interested in descriptive statistics), I'd like to say that there is either a ...
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1answer
70 views

What is the honesty condition for regression trees?

I have a question pertaining to Stefan Wager's "Asymptotic Theory for Random Forests": http://arxiv.org/pdf/1405.0352v1.pdf Wager first states that trees are "fully grown in the sense given training ...
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44 views

Wilcoxon signed rank test - Normalize data or not?

I am comparing my algorithm's performance with other algorithms, for a minimization problem. There are ten different benchmark problems, for which I have computed the average solution quality for all ...
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18 views

Which statistical tests requires one to know the sampling error?

I would like to know which statistical tests requires one to know the sampling error? I am planning on using an existing public online panel that is representative of the UK population by age, gender ...
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1answer
27 views

How do I figure out low, high, and median scores?

I am not sure how to make this a problem and solve it. It's statistical data that I am trying to figure out for a paper I'm writing. Basically, I am scoring candidates with 9 questions. Here's an ...
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3answers
216 views

versus (vs.): how to properly use this word in data analysis

This question is probably more about the English language than statistics, but I have decided to ask it here anyway. When we compare two groups of samples, let's say Treatment vs. Control, and we ...
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2answers
251 views

Approximate mean from .25, .5, .75 percentiles

If I have median (.5 percentiles), and the .25 and .75 percentiles, what is the best guess of the mean? If the .25 and .75 percentiles are in the middle of a probability mass with weight .5 (.25 on ...
2
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1answer
29 views

What statistical method is most appropriate?

I am testing the differences between men and women pertaining to the perceived origin of criminal behavior. I distributed a survey with multiple choice options to pick what each individual thought the ...
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1answer
87 views

Using a rolling window in time series regression

I am learning about regression. I have done some cross sectional regressions which are fine. I recently did a simple time series regression. So I have a y & x vectors each containing 1000 ...
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39 views

Error bars on graph, skewed data, negative standard deviation

I have only had basic stats. I conducted some research where I have four different treatments and results for the data range from 0-6. I don't need any elaborate stats test, I just want to know how I ...
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3answers
62 views

interpret scatter plot if there is anything to interpret from it

I have an x variable and a y variables. I have done a simple scatter plot. I however don't really know how to interpret (if there is anything to interpret) the plot. I can't find any other similar ...
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2answers
77 views

Change scores as outcome measurements in clinical trials

I am performing a Meta-Analysis about a mental disease, comparing intervention vs. control groups and try to extract outcome results from published study papers. In some clinical randomised trials ...
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13 views

Likert scale analysis , how to analyze it in this case?

I have a questionnaire divided in 4 section. Each section has 5 question ; all of the questions are using the likert scale of 7 points (strongly agree, agree..etc..) I want to compare the 4 ...
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1answer
52 views

interpreting NMDS ordinations that show both samples and species

I am using the vegan package in R to plot non-metric multidimensional scaling (NMDS) ordinations. I am using this package because of its compatibility with common ...
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1answer
45 views

MSPE formula - is the number of variables not important?

The formula I usually see for MSE is: $$\mathrm{MSE} = \frac{\sum\limits_{t=1}^T e_i^2}{n-k-1},$$ Whereas for MSPE it is usually: $$\mathrm{MSPE} = \frac{\sum\limits_{t=T}^{T+P} e_i^2}{P}.$$ So ...
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23 views

Deducing an approximation to the Gini coefficient

Assuming we do not know the Lorenz curve function, If $(X_k, Y_k)$ are the known points on the Lorenz curve, with the $X_k$ indexed in increasing order $(X_{k – 1} < X_k)$, so that: $X_k$ is the ...
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4answers
1k views

Why shouldn't the denominator of the covariance estimator be n-2 rather than n-1?

The denominator of the (unbiased) variance estimator is $n-1$ as there are $n$ observations and only one parameter is being estimated. $$ ...
2
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2answers
50 views

Conceptual understanding of standard deviation

I always understood standard deviation to be the average distance of the observations from the mean. But when I generated a standard normal distribution N(0,1) with n = 1,000,000 in Excel, and took ...
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15 views

Month Wise Descriptive Statistics

I have a Large Data Set of prices, Spanning across 15 years, I need to find out descriptive statistics? The Problem is there is a Trend Element in the Data, hence I need to break up the descriptive ...
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1answer
114 views
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51 views

Similarity between two samples (2D matrices)

I have two matrices: A= 4000x78 where 78 is the dimension of features and 4000 is the number of samples. B= 1000x78 where 78 is the dimension of features and 1000 is the number of samples again. ...
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3answers
200 views

What is the difference between variable and random variable?

I know that "variable" means "values which vary." In a simple linear regression model : $$Y=\beta_0+\beta_1X+\epsilon$$ $X$ is variable that is the values of $X$ vary. Why is $X$ not a random ...
2
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1answer
177 views

QQ plot in Python

I generated a qq plot using the following code. I know that qq plot is used to check whether the data is distributed normally or not. My question is what do the x and y axis labels indicate in qq plot ...
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26 views

Frequency polygon area

If I have a histogram with bins equal width, then the area of the histogram is the same as the area of the frequency polygon. What about if we have an histogram with bins of different width? I think ...
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20 views

Creating A weighted Scorecard using Stats

Im new to forum and have tried reading some articles to solve my problem but had trouble understanding some of it and others might not have been completely relevant. Below I will outline my problem ...