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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47 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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15 views

Mathematical notations for random variable and average from discrete set

I have a set data-set with the following structure, resembling ratings: UserID |ItemID | Score I have some algorithms that will predict the score of a user-item ...
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10 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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57 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 ...
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6 views

Looking for catalog of “mechanism classes” that give rise to specific curve shapes

(I apologize for the length of this post. I don't know how to frame the question more succinctly.) I have some experimental data, in the form of a collection of curves with fairly little noise, ...
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1answer
18 views

Is there a value to show how fragmented is a group?

I would like to know if there is a way to calculate a number that can show how fragmented is a group? It should be something like "variance of categorical data"? For example I want to see how ...
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10 views

Given MTTF and Number of Items, how to calculate failing parts with Time?

I am wondering how to make use of MTTF Here is the situation, I am given an MTTF for an item type x and a certain demand for that item in the next 25 years, say 100 parts that will be in operation ...
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13 views

Response Rate in Research

I want to ask about response rate. I have distributed 2500 posts. However, I have received back around 30. Then, I sent 200 posts as reminders with appealing letter. I have received one or two only. ...
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1answer
80 views

Error on interquartile range

How can I compute the error on the interquartile range of a sample? By error I mean its std deviation (e.g. error on the mean = RMS/sqrt(N)). The sample is from a unimodal distribution, similar to ...
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1answer
27 views

How can I statistically formulate football player attributes similar to Football Manager games or footballdatabase.eu?

I have collected player match history statistics like runs, shoots, passes and such. I would like to come up similar attribute values (psychical, mental, technical) to Football Manager game or ...
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28 views

Formula for “adjusted mean” - Is this correct?

I am working on a software project involving statistical analysis of myoelectrical signals (EMG). One client requested the calculation of "adjusted average" for a given signal interval. His ...
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30 views

Different means with barchart and descriptives in SPSS

I have a dataset (in SPSS 22) with different measurements of children, with the children in rows and with the measurements as variables in the columns. For example, the activity levels of the children ...
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17 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 ...
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9 views

What kind of statistical method is recommended to compare ratio in pre-test and post-test

I want to compare two different ratios. When this ratio is close to 1 it shows the better stability in the body. Would you please guide me that which statistical test is better for this situation? ...
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22 views

R statistics interpretation [duplicate]

I am learning exploratory statistical testing methods in R. Specifically I am trying to learn single variable linear regression. I was hoping that someone would be able to give an explanation of the ...
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28 views

Simple descriptive statistics in SPSS or Excel

Apologies if this is a stupid question. I have a data-set with 3109 people They were asked to say whether they thought Reason 1, Reason 2, Reason 3 and Reason 4 were good reasons for having a ...
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1answer
54 views

numerical measure for an ordered list

At the end of every semester I have to input my students' grades into a database. Typically this means I go one by one down my list of grades from my excel spreadsheet and manually fill the grade into ...
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1answer
186 views

ECDF [skewed] distribution, wish to mean adjust to .5

I have a distribution that is skewed to the left (i.e. a lot of low values, aka positive skew - verified) Basically, I have either a lot of similar low [~minimum] values, or 0 values, or something ...
2
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1answer
27 views

Estimate Mean and Standard Deviation from Percentiles

I have a derived dataset that specifies the percentiles from the 10th to 95th in increments of 5 along with the total number of data points. Is there a way to estimate the mean of the original ...
2
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1answer
39 views

Estimate median from mean, std dev, and/or range

I have easy access to the the mean, standard deviation and min/max values for a variable. I also have the number of elements used to compute those values. The data is real numbers with an absolute ...
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26 views

What's the sample size required to confirm that two treatments are identical?

Goal: Determine if a machine is defective Say I am going to give the same treatment to a group of people. I have a machine that will randomly split them into $2$ groups before giving the same ...
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1answer
22 views

Statistical Test for seeing differences in a single sample

So I've been trying to analyze 3 repeats for some data (essentially, a single independent variable measured at three different times), which would look like something like this: Test 1 [Value] Test ...
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20 views

calculate returns for volatile time series

Background: I want to compare two trading strategies in term of profitability. The red one is an active trading strategy, which involves many entry and exit to a specific market. The blue one is a ...
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32 views

Subtracting mahalanobis distance in one direction from total

Sincere appologies for what may be a stupid question, I'm new to pattern recognition and have exhausted all the textbooks which are aproachable to a beginner. I have substantially reworded this post ...
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34 views

Are standard deviation, CI95%, mean, median computed in the same way for uncorrelated and correlated (time series) data?

My question is pretty simple. Descriptive statistics, like mean, median, sd, etc... for time series data with just 9 points are computed in same way as for uncorrelated data? Or the mathematics is ...
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2answers
74 views

Derivation of the Simpson index

I'm interested in the derivation of the Simpson diversity index. I found the normal interpretation of this index, but I'm not able to see what's the "mathematical background" of the formula. I read ...
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50 views

How to calculate a maximum standard deviation? [duplicate]

I have a test which contains 24 items, so the maximum result is 24 and the minimum result is 0. How can I calculate the maximum standard deviation possible? Thank you!
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29 views

find relevant statistical distribution of data

i would like to find maximally relevant statistical distribution of sinusoidal data,for example let us consider following model ...
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22 views

Reading a crosstabs

I am confused and struggling to read this simple crosstabs. I am trying to create a profile of downloaders. One of the demographics I am looking at is age. Should I be looking at the percentage ...
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36 views

Use PCA for pattern recognition

I have always used PCA as a preprocessing techniques. There are some people that use it for pattern recognition. Once I used pca to project my data in a 2 dimensional space and then I observed that ...
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1answer
31 views

How to compute Prior Variance

This might sound a little silly to ask, but I couldn't figure out how an author arrived to the prior variance estimates from this vector: ...
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8 views

Looking at what content by type of downloader

What statistical analysis test do I need to run? I want to compare type of downloader (Legal and Illegal) to what type of content they download (Music, Movies etc). In SPSS I have set the type of ...
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1answer
98 views

Strength of association test with binary variables

I have a dataset with different purchases for two different items from the same users. So the users purchased the two items at different points in time. I also have 3 different variables: ...
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10 views

How do you do a power calculation for a 2-phase prevalence survey?

I'm trying to work out what sample size I need to calculate a prevalence rate within certain confidence intervals, using a two-phase design. There is a screener test. Everyone that screens positive ...
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27 views

Relation between median follow-up and median survival?

When follow-up is assumed to be constant and variable, is there any relationship between median follow-up and median survival? I.e. should one be less or greater than the other?
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26 views

Determine the significance of factor variables

I have a df like this: ...
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19 views

Can composite scores of Likert scale be obtained? [duplicate]

I am using a Likert scale for a group of 3 questions. Strongly Agree Agree Undecided Disagree Strongly Disagree I have 3 questions with these possible responses under the category "Effectiveness". ...
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74 views

Scale independent forecast error metric that works with changing signs

I am trying to analyze a quite large (~25,000 rows) dataset of cash flow forecasts. Receipts and expenses are aggregated, thus I may end up with the following data: ...
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1answer
129 views

Bootstrapping approach: how is the resampled sample chosen?

Bootstrapping approach is based on the assumption that the sample is the population. Then, a resampling of the sample is done, replacing the individuals of the population by chance. The number of the ...
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1answer
80 views

Establishing the lack of randomness in lottery number selection

Related to this question, if I have 1500 or so jackpot results from a 6/49 lottery (numbers drawn, number of winners and prize per jackpot winner), how can I demonstrate that some numbers are less ...
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64 views

Does confirmatory = inferential, and exploratory = descriptive analysis / statistics?

Reading this webpage, I wonder: Are confirmatory analysis / statistics and inferential analysis / statistics the same concept? Are exploratory analysis / statistics and descriptive analysis / ...
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2answers
301 views

Is confirmatory vs exploratory statistics “induction vs deduction”?

This webpage says: Inferential Statistics - Deductive Approach Descriptive Statistics - Inductive Approach But I doubt it. If I understand correctly, Inferential Statistics is "given ...
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2answers
58 views

Range of a centered, reduced sample drawn from a bounded domain

Assume you draw $N$ values from a bounded set, say $[0, 1]$ without loss of generality. If I am right, the centered values $X-m$ will remain in range $[{1\over N}-1, 1-{1\over N}]$ (by considering ...
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18 views

Measures of consistency and magnitude for hourly data?

I have 3 months of data, collected on an hourly basis, that measures how many events (0-10k) occured in each hour. What is the most scientifically rigourous means by which I can generate statistics ...
3
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1answer
150 views

Generate two variables with precise pre-specified correlation

I want to generate two variables with (pseudo-) random numbers with an exact pearson's r. How do I do that? Python and/or R solutions would be nice! I am able to generate random data that ...
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1answer
104 views

Problem with identifying outliers

I'm running a biological experiment with rodents, have two groups (each consists of 26 animals), where one is treated with a chemical, and one is control (saline). In one variable, there doesn't seem ...
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3answers
309 views

Descriptive and Inferential vs Parametric and Non-Parametric Statistics

Are the concepts of descriptive vs inferential statistics and parametric vs non-parametric statistics orthogonal? As in, can we have a descriptive parametric statistic or a descriptive non-parametric ...
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1answer
77 views

Several items for one construct

I am a dummy in statistics but need to accomplish some simple survey analyses. My question is: if I have several questions (items) for one construct (say, questions JS1-JS3 for job satisfaction) with ...
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51 views

Exponentially weighted average of data stream variance

For modeling a sequence of data, I once heard the technical term of "exponentially weighted average of the data stream variance". It is defined recursively as I am not clear why does this recursive ...
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1answer
284 views

Comparing the variability of two different large data sets

I have two data sets, one data set contains value in the range of 10,000- 1,000,000 and other data set contains the value between 1,000-10,000. I want to compare the variability means,which data has ...