The descriptive-statistics tag has no wiki summary.
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Characterizing uncertainty in empirical PMF of unknown discrete random distribution
Suppose a discrete random distribution $X$ which takes integer values in some small (but not binary) range, e.g. $[0, 255]$ and whose true pmf is unknown (however, the null hypothesis is that it is ...
2
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1answer
57 views
Can I use 95%CI for mean for non-normal distribution if there is a natural limit?
I have problem with real basics. I have variable that has p=.000 in Shapiro-Wilk. As I looked on the histogram it appears that the cause is natural limit for this measurement (value 0, skewness > ...
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1answer
9 views
Macro and Micro Inter-Coder/Rater Agreement
I have a labeling task with 4 labels for which I'm using 2 coders/annotators/raters. This labeling effort leads to a confusion matrix like the one in
...
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1answer
87 views
Why is the coefficient of variation not valid when using data with positive and negative values?
I can't seem to find a definitive answer to my question.
My data consists of several plots with measured means varying from 0.27 to 0.57. In my case, all data values are positive, but the measurement ...
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15 views
Calculating Needed Sample Size
I intend to run a study in which I measure individuals along 20 variables, introduce an intervention, and then measure them again. My plan was to analyze the data via a repeated measures ANOVA, but ...
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1answer
371 views
How do I interpret the results from the F-test in excel
I have a fairly simple question regarding the interpretation of the F-test in Microsoft Excel.
Let't say these are the results of my F-test:
http://i.imgur.com/ZLzEQih.jpg
I am now wondering how to ...
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3answers
230 views
Generate distribution based on descriptive statistics
There's a hidden variable that I'd like to approximate. I know several summary statistics: min, max, mean, median, standard deviation, n; and that it's approximately normal.
I can obviously do a ...
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124 views
How do I know whether I need to normalize before ranking?
Update
Experimenting with descriptive statistics, I determined that if rank the scaled weighted average quantity for each set, computed as follows:
$$Mean(Weighted Quantity) * \frac {Median ( ...
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1answer
61 views
How to calculate t-values from percent ranks?
A norm-table from a psychological test is giving percent ranks (PR).
How can I transform those into t-values by calculation? (Assuming normal distribution.)
I found a lot of references on how to ...
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1answer
32 views
sketch distribution
Brand new to stats and trying to solve this exercise that I found online. I don't want you to solve it for me, I just need a starting point to solve it myself.
By "sketch" do they mean to show the 20 ...
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82 views
Control chart Xbar and R missing values
I am taking a business statistics course and I can't seem to figure out how to find the missing figures in the following problem; here's the question:
Using the data below, determine the trial ...
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1answer
85 views
Inequality involving interquartile range and standard deviation
Suppose I have a finite set of observations $x_{i}$, $i = 1, 2, \ldots, n$. Are there any inequalities relating the standard deviation and the interquartile range?
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36 views
Choice of population to study
I want to do classification or clustering of my big data set on web applications.
I would like to cluster website visitors who are identified by their cookie ... which they can drop whenever they ...
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1answer
53 views
Creating a descriptive table
I am having trouble trying to figure out how to report categorical and continuous data in one table. I want to create a descriptive table summarizing some of the categorical and continuous data from ...
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1answer
349 views
kurtosis and skewness - descriptive statistics
I would like to describe the "peakedness" and tail "heaviness" of several skewed probability density functions.
The features I want to describe, would they be called "kurtosis"? I've only seen the ...
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39 views
How to describe the serial data with some values under detected limitation?
I have the data as below, I wonder how to describe it correctly.
The limitation of detectable concentration is 0.375, so, sample 3, concentration at d0 and d6 was undetected. How can I describe the ...
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Estimation of temporal onset and duration of growth from irregular count data
Suppose I have census (count) data for a migratory species passing through a set of locations, at irregular intervals -- $n(i,t)$ is how many individuals were present at location $i$ on day $t$ for an ...
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24 views
Normal distribution problem [duplicate]
Possible Duplicate:
Help with homework with Normal distribution
Problem 5.21 Newbold See image
My attempt:
1. See image2
Searching for it in a Normal Distribution Table]
I find z=0.06
...
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1answer
50 views
Are there any formal definitions or statistical theories about this kind of events?
Say a basketball team wins a game. Obviously, at some point in the future, the basketball team will lose a game. So hence, after each game that the basketball team wins, the team is edging closer to ...
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2answers
187 views
Is this flawed statistics?
I often see similar statements on football (soccer) websites.
Team A has lost 4 out of their last 5 matches against Team B. (and thus, there is a high chance Team A will lose their next match ...
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1answer
210 views
Reporting chi-square tests for weighted data
I was wondering if you could share your experience in reporting chi-square tests for complex survey data in journal publications. Normally Chi-square tests are reported as $\chi^2_1(2,\text{ N} = 90)= ...
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1answer
130 views
Descriptive measures for 2x2 crosstabs with zeros
For 2x2 contingency tables I already know the RR (Relative Risk) and the OR (Odds Ratio). However none of these two is good dealing with empty cells in the table.
| A | -A |
B | n11 | n12 ...
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32 views
Statistic describes the sharpness or dispersion of sequential data?
I want to find an existed statistic that can clearly describe the sharpness or dispersion of a peak-shape signal. To state this question more clearly, I plotted two different types (sharp and broad) ...
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What statistics are sufficient?
Can anyone help explain why the following statistics are either Sufficient or not Sufficient?
Mean, Median, Mode, Standard Deviation, Variance, Range, IQR, Skewness, and Kurtosis.
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2answers
83 views
Visualizing two variables which have a very similar values
I have two columns of data, and would like to show their differences through the visualization approach. The current issue is that these two columns are in-fact very close to each other. In other ...
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2answers
170 views
Sampling weight when using regression or descriptive statistics
I came across sampling weight when I was looking into analyzing survey data.
I was wondering whether we need to take into consideration sampling weight when we are running linear/non-linear ...
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1answer
81 views
What to look for in a pocket calculator for a Graduate level statistics course midterm / final [closed]
Soon I'll be sitting for a midterm (and then the dreaded final) for a graduate class in Statistics.
It's open book / notes but I'll be needing a calculator -- something I've not used for years.
Any ...
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2answers
183 views
Rules of Thumb to choose an initial number of class intervals and refine that choice (potentially automatically)
I was wondering if there are established rules of thumb (or algorithms) that, given a set of observations can help:
choose an initial number of class intervals.
refine that choice to a better ...
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1answer
537 views
How do you treat 'don't know' answers for a composite likert scale?
I'd like to create a composite item from variables with the following scale: strongly disagree, disagree, neither agree or disagree, agree, strongly agree and don't know.
I was going to code the ...
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1answer
325 views
What test will tell me a normalized percentage of the data?
I'm working with baseball statistics and I have a list of the players' batting percentages. I want a formula that will tell me what percentage of the data is represented from a player's score ...
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2answers
221 views
How to estimate the third quartile of binned data?
Is there any technical trick to determine the third quartile if it belongs to an open interval which contains more that one fourth of the population (so I can't close the interval and use the standard ...
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1answer
299 views
Is it possible for quartiles to have uneven groups?
If I have a data set with many values repeated (example below) how would it be divided into quartiles? I assumed at first that the quartiles would be uneven, but every single definition I've read ...
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2answers
574 views
Is the sample variance a useful measure for non-normal data?
Does it ever make sense to compare the variance for two sets of data, neither of which are even approximately normal (e.g. bimodal)?
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Exploring and visualizing survey data collected on small sample
I'm doing some analysis on survey data. Unfortunately the survey isn't as well set out as a data specialist would like and as a result I'm trying to find some innovative ways to examine and visualize ...
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3answers
194 views
Assessing the accuracy of a deterministic mathematical model
How can assess the accuracy of the output of a deterministic mathematical model?
For example, a climate model can predict the mean annual temperature (MAT) for a specific location. I can use the ...
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1answer
138 views
Mixed text and graphical univariate data summary in R
One standard approach we use when describing our data for a paper is to cut our dependent variable into tertiles and then give mean/SD or median/IQR for each tertile for continuous and ...
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2answers
229 views
Panel-data exploratory data analysis
I have a dataset for around 40k firms over fiscal years 1950-2011 with about 430k firm-years. If I'm not mistaken I have panel-data. In addition, the firms are nested within 9 industries.
I created a ...
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2answers
72 views
How to detect variables discriminating a sample from the rest of the samples?
I have a traditionally structured data set where rows are observations and columns are variables. There are only a few observations but comparatively more variables. The observations are regions of a ...
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1answer
1k views
Panel data descriptives, plots and 'feel for the data'
Allright, so I have a dataset for around 40k firms over fiscal years 1950-2011 with about 430k firm-years. If I'm not mistaken I have panel data.
I created a unique identifier ...
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1answer
67 views
Inconsistent results from attempting to count matching values in lists within data frames in R
Pretty new to R and to stackexchange. My apologies if I make any faux pas.
I'm working with the North Carolina births data from irss.unc.edu. I have a data frame ...
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4answers
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Modern successor to Exploratory Data Analysis by Tukey?
I've been reading Tukey's book "Exploratory Data Analysis". Being written in 1977, the book emphasizes paper/pencil methods. Is there a more 'modern' successor which takes into account that we can ...
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1answer
478 views
Interaction terms interpretation
How do you interpret an odds ratio of an interaction between two continuous variables $x_1, x_2$? Would you fix $x_2$ and let $x_1 = x$ and $x_1 = x+1$?
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2answers
119 views
Is it possible to make quantitative comparisons using income inequality metrics?
I've calculated income inequality metrics (Gini/Hoover/Theil coefficients) for several populations. I know I can make claims like "this population has a higher Gini coefficient, so its distribution in ...
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109 views
What is the income distribution in the U.S., in 1% increments? [closed]
Where can I find a roughly complete CDF of income in the U.S. (not simply the Gini coefficient or a point summary like "X% of the population make Y% of the income?")
Note: I think this may be ...
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1answer
327 views
Calculating the Standard Error of the Mean (SEM) of a sample from the SEMs of two subsets of that sample
Can you calculate the Standard Error of the Mean (SEM) for a set of data given the SEM from two subsets of the data? How would you do this?
(The two subsets are mutually exclusive and exhaustive.)
...
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1answer
265 views
Forecasting a “chaotic” time series
Here are four graphs,
1, autocorrelation, autocovariance, partial-correlation and cross-correlation calculated from a time series are given.
2, The time series
I need to do some predictions on ...
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145 views
Describe the distribution - too few data points
I'm struggling slightly with part of a homework problem. We are asked to
"describe the distribution of weights, at the school level"
There are n=220 students in total
There are p=38 schools
I have ...
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2answers
954 views
What descriptive statistics should be reported in tables and graphs when using Friedman's nonparametric test?
I'm using Friedman's nonparametric tests for repeated measures for my thesis (I tried transformations on all variables first but data was still highly skewed) and had 2 questions:
What are the best ...
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2answers
1k views
How can I calculate the confidence interval of a mean in a non-normally distributed sample?
How can I calculate the confidence interval of a mean in a non-normally distributed sample?
I understand bootstrap methods are commonly used here, but I am open to other options. While I am looking ...
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3answers
1k views
What does “unbiasedness” mean?
What does it mean to say that "the variance is a biased estimator".
What does it mean to convert a biased estimate to an unbiased estimate through a simple formula. What does this conversion do ...
