# Tagged Questions

A brief numerical description of a set of data.

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### Advice on the statistical analysis of clinical data using summary statistics, t-tests, ANOVA, and linear regression

I need some help with the statistical analysis of a study of a particular surgery to remove a particular cancer. I am using the statistical program R to conduct my analysis. My data are saved in the ...
24 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 ...
319 views

### Calculating the percentage change of 2 values

If I have two different percentages and I wanted to know the change, I would simply use the percentage change formula...but what if I want to compare two percentages that have different amounts: Ex: ...
318 views

### How do I compare the accuracy of two measurement devices when one of them is the reference?

I'm currently trying to compare the measurement accuracy of two devices. However, I am using one of the devices as a "gold standard" to say something about the accuracy of the other device. The ...
76 views

### Summary statistic for an error measurement

I have $n$ error measures that can be positive or negative values. Negative values are more important for my experiment than positive values. Of course, taking the mean of the $n$ values doesn't make ...
2k views

### Tukey's Hinges: Grouping Data

I am having trouble figuring out how to group data using the inter-quartile ranges calculated with a box and whiskers plot as well as looking at Tukey's Hinges. I understand the IQR and Tukey's hinges ...
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### Unpaired t-test with only summary means

Is it appropriate to conduct an unpaired t-test with only summary means from both groups? For example, let's say you want to compare: a. Professor A's scores received on a evaluation by his ...
61 views

### Sample vs. Population

I'm trying to analyse the performance of my server by collecting performance data using standard tools such as Windows Performance Monitor, and then putting this data on Excel for analysis. When I ...
250 views

### Quantiles for non-normal cdf

When I compute the five-number summary on my sample, I obtain quantiles that differ from the quantiles I got from the empirical cdf, since they are not normally distributed data. Can you help me in ...
124 views

### Interpretation of descriptive statistics for dummy variable

How can I describe descriptive statistics for a dummy variable (gender of worker in a shop)? Let's say this is the info that I have: ...
55 views

### Finding the distribution when the observations are dependent

How do we find information about the distribution of a variable in presence of dependency among our observations? This dependency is coming from measuring the variable on the same group of subjects ...
631 views

### Statistical test suitable for small dataset (n=25)

I have a dataset of cases and age & sex matched controls (n=25). I need to do a statistical test to find the significantly different incidences of ICD-9 codes using a p-value or similar measure. ...
51 views

### Calculate how big a variable is in relation to others

This will sound weird, but I'm trying to calculate something that I don't know the name. I want to calculate how big/low a variable is in relation to the others. Like Google webmaster tools says ...
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### What is the best method of performing a chi-squared test with only one set of data?

I am trying to perform a chi-squared test on the following data: Achieved: 31 Expected: 19.87179 From a total of: 182 Is it possible to perform such a test on just one item of data like this? All ...
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### Hypothesis test for summary data involving percentages

500 patients had an operation to remove stomach cancer. There exists a clinical guideline that suggests that a minimum of ten lymph nodes should be removed during the operation. I am therefore ...
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### How can you summarize growth in the “production” rate per person?

I have been reading the book, Good to Great by Jim Collins. It says that you should focus on information that "cannot be ignored," and that you should focus on the right "denominator." I thought it ...
405 views

### How to graph quantitative and qualitative improvement in human health related measures?

I'm creating an app that logs daily data from my users. Data includes: waist circumference, weight (Quantitative data) certain conditions like psoriasis, migraines, fatigue (Qualitative data rated ...
3k views

### The formula for finding the mode of grouped data

Here is a link that describes the formula to find the mode of grouped data. Here is a link that gives a graphical method to finding the mode of grouped data. Question: Can someone please explain how ...
75 views

### kurtosis, positive skewed and negative skewed for probability distribution

When discussing probability distribution, I always read something such as excess kurtosis, positive kurtosis, positive skewed and negative skewed. What exactly do these concepts indicate? In practical ...
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### Quantify the difference between two samples

My problem is this: I have a need to do some analysis of student test results, and I am seeking some tools in order to do so. What I have are collections of scores for a number of different tests, and ...
33 views

### Classes of asymptotically normal statistics

Consider an iid sample $X_1, \dots, X_n$, from a "well behaved" distribution with pdf $f(X)$. My question is the following: what are the classes of statistics $S(X_1, \dots, X_n)$ that are ...
286 views

### Hamming distance for strings with different length

I am working on a project that involves computing similarity metrics between strings. I was would like to know whether it is possible to use hamming distance on strings with differnt length, and if ...
85 views

### Statistical test for finding the effect magnitude of different causes

I am fairly new to statistics and would wish to find out if there is a statistical test that tells me the magnitude/contribution/importance of different causes over a perceived effect. For example, ...
88 views

### Average of rate of change in a set of independent change events

What is the right method for computing average of percentage values? Arithmetic average, geometric average, or something else? Here's an example of problems I'm talking about. Suppose for years 2009, ...
312 views

### How to best represent median proportions using stacked bar charts?

I have a large dataset with several responses about an organization's labour costs. I would like to represent this data graphically. Typically what we do is provide a stacked bar chart (using R) of ...
159 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 ...
105 views

### Charting errors based on number of items per month

I'm a complete noob when it comes to statistics, so please excuse my lack of standard terminology. I think my question might be related to normalization, but please re-tag if I'm wrong. I'm a ...
31 views

### Non-parametric z-score for comparison of outliers/extreme values across set of non-normal distributions

I have a network and for each node in the network I am calculating a certain property, essentially its 'connectedness' to a set of source nodes. In order to identify nodes which are better connected ...
22 views

### Explaining the difference between error propagation and “grand variance”?

I have the following data concerned with simple radiation detection. I collect a background dose $B$ for 100 seconds and find the standard deviation and get the uncertainty $E_B$. I then take 10 ...
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I basically have a timespan from January until August (or any other timespan) which is divided into active periods (denoted by a red line in the plot) and inactive periods (the rest). What I want to ...
161 views

### Implementing a Kolmogorov-Smirnov permutation test

I would like some advice on how to implement a Kolmogorov-Smirnov test. This is a condensed version of my previous question -- any further detail can be provided if needed. I have data from n ...
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### Guessing data from statistics

If I have a number of statistics/information of a data set, e.g. mean, SD, skew, kurtosis, % data values within a certain range, etc, how might I go about trying to deduce a portion of the actual ...
60 views

### How do I best estimate population parameters from multiple sets of summary statistics on one sample?

Suppose that I have an assortment of summary statistics on a sample, and some beliefs about the underlying distribution, but no access to the sample itself. Each of the sets of summary statistics is ...
37 views

### Study- Probabilities problem

Can some of you tell me why the following holds true?: $P(A \& B^C )= P(A)-P(A\&B)$ in which: $B^C$ is $B$ complement. In which: $A$ and $B$ are independent. thanks..
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### What types of statistical analysis should be done for testing ISP connections?

I'm in the middle of analyzing data taken from testing two different ISP connections (cable and DSL). I've been running randomized testing on the two connection using three different tests which all ...
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### How to reliably estimate a random sum of unreliable elements?

This is an ill posed problem I'm faced with at work. I have observations $X_i$, $i = 1,2,3,...N > M$. I need want to compute $S = \sum_{i=1}^M X_i$. Unfortunately, $M$ is random, and extremely ...
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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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### How to compare yearly categorical data?

I have location data from 5 years (>30,000 points). Each location is given a classification name (in my case vegetation classes). These vegetation classes were assigned by intersecting the locations ...
62 views

### Summarising wind vector statistics over time

My problem is to figure out an algorithm for summarising wind statistics over an area. The statistics are (24x) hourly but I want to end up with 2-3 'blocks' that summarise the conditions for the ...
233 views

### “The statistician should set the probability of Type I error as low as possible”

Do you agree with the following statement? Why or why not? I disagree with this statement but i have no reasons to back up.Anyone can help?
105 views

### Strange behavior of R function ecdf

I have a very long vector, x, of integer values in the range [0, 1000]. I then use stats::ecdf to create empirical cummulative ...
132 views

### Question on Survival Analysis

I'm working on a survival analysis project. In part of the project, I'm asked to "identify factors that may contribute to an increased risk of death". I have difficult time understanding what I'm ...
198 views

### Hidden Markov model implementation [closed]

I've been looking for the internet explanation about the hidden Markov model (HMM) and its implementation but I think there's not quite good explanation. Does anyone know and guide me through this ...
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### What is a good way to compare similarity between datasets with little variance?

Let's say I have a list of 100 MLB pitchers and 5 statistics for each of them. The difference between, for example, an ERA of 3.5 and 3.1 might not look like a lot to a naive similarity algorithm, but ...