The expected value of a random variable; or a location measure for a sample.

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9 views

How to calculate Mean and Standard deviation in Lognormal distribution where only P90 and P10 are known

I have P90 and P10 of a lognormal distribution. P90=142.56 and P10=3415; I need to estimate the mean and standard deviation of this lognormal distribution. I have done the following steps and then ...
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2answers
155 views

The average of mean and standard deviation

I have the mean and standard deviation for body temperature ( in a group of people n=10 ), which measured using a thermometer in the left axilla, then in the right axilla ...
3
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1answer
55 views

How do I find the expected value of F(isher)-distribution

$E(F)=\int xf_{k,m}dx$ where $f_{k,m}(t) = \Gamma(t)=\frac{\Gamma((k+m)/2)}{\Gamma (k/2)\Gamma(m/2)}k^{k/2}m^{m/2}t^{k/2 - 1}(m+kt)^{-(k+m)/2}$. How do you find $E(F)$? Say you have to convert ...
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0answers
13 views

Running svy: mean VAR1, over (var2) [closed]

I am trying to run this command: svy: mean VAR1, over (var2) but it tells me invalid syntax if var2 is a float and no observation if var2 is a string. Funny ...
3
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1answer
39 views

When confidence intervals of two parameters do not overlap with the mean of the other, why is it considered to be statistically significant?

Consider two parameters with means A and B with 95% confidence intervals. If the confidence intervals of the parameters do not overlap with the mean of the other, why is it considered to be ...
-1
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1answer
29 views

Learning Statistics [closed]

I am new to statistics and I am trying to get my head around 'why' some of these are calculated the way they are and what they mean, or were they just made a preference that stuck? - the statistics ...
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0answers
28 views

ANOVA : mean or variance?

I am confused about the ANOVA method in Statistics. ANOVA stands for analysis of variance. It is used to compare the mean between several groups. We use a test of variance (Fisher) for ANOVA. So, is ...
5
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2answers
281 views

What does it mean to say that “the population mean is a single fixed number?”

I am trying to figure out what it means if a population mean value is fixed.
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0answers
31 views

Good algorithm to compute the sample mean and variance [duplicate]

I am looking for good (fast, memory efficient, ideally one-pass) algorithms to compute the sample mean and variance. I have found a technical report by Chan, Golub, and LeVeque from 1983 with ...
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1answer
16 views

Test for significance of peaks (maximum) in time series

I have a time series of values, something like this: ...
1
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0answers
14 views

Cross correlation of gaussian signals with its mean signal gives non-gaussian distributed scores

The following is my question: I have signals that contains noise, they are of the following form see the figure below.. Then I take the mean signal of all these signals (identical in length and ...
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0answers
24 views

Probability of Non-exceedance modelled by Normal Distribution Question

The complete question is: A number of pre-cast beams are to be laid side-by-side to form a bridge deck which will later receive an in-situ topping. The beams are nominally 300mm wide, but in practice ...
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0answers
14 views

Outliers detection or some roubust metrics on long tail sqewed distributions

I have a distribution of user sessions on the web site in the following format date,sessionId,price 2010-01-01,1,0 2010-01-01,2,0 2010-01-01,3,10 ... And I am ...
0
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1answer
30 views

Measure of Central Tendancy in ARIMA?

I know very little about the ARIMA - the AutoRegressive Integrated Moving Average - model but I am interested in what type of central tendency is represented by "average". Is it simply the mean? If ...
1
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1answer
20 views

Measuring forecast accuracy of the conditional mean

Consider a dependent variable $y$, independent variables $x_1,\dotsc,x_K$, a model $$ y = X \beta + \varepsilon $$ and an estimated coefficient $\hat\beta$. If the model is assumed to be well ...
1
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1answer
25 views

Compare several means with different sample sizes (greater than 2)

I have seven different groups with different sample sizes and variances and I want to compare the means of their data. I'm not very informed in statistics, so could anyone help me out here? I've only ...
0
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0answers
16 views

Anova Profile Plot - Estimated Marginal Means understanding

I would like to ask you a question with regards to the Profile Plots generated by SPSS for 2x2 ANOVA (with balanced design). I have two Independent Variables, each one with 2 levels, and a Dependent ...
0
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1answer
19 views

Can one calculate a general mean for questions that use different scale length?

I have two sets of questions: 1). 5 questions with answer options from 0 to 10 (very unsatisfied to very satisfied) and 2). 9 questions with answer options from 1 to 6 (same meaning) The study was ...
0
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0answers
21 views

Real world example where mean is multiple orders greater than the standard deviation

This question is related to my research work. As it says in the title, I wanted to know if there exist any real world examples where the mean is multiple orders of magnitude larger than the standard ...
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0answers
12 views

Bird eye view of unknown data set [duplicate]

Pardon me if this question does not fit this site (or SE engine in general) but I do not know where to post it. Suppose that you have unknown data set which you want to explore. What ...
19
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9answers
3k views

Regression to the mean vs gambler's fallacy

On the one hand, I have the regression to the mean and on the other hand I have the gambler´s fallacy. I have had a good performance in the last game and, according to the regression to the mean, ...
0
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0answers
6 views

Detecting and Identifying Superpositioned Normal Distributions

I have data with populations centering around two means, one higher and one lower, as shown in this histogram. Is there a standard mathematical or algorithmic way for me to detect this occurrence ...
2
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3answers
910 views

If the mean and median underestimate the true central tendency, why use them?

In skewed distributions, both the mean and the median can easily underestimate or overestimate the true central tendency. For example, have a look at this violin plot: The median is shown here in ...
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0answers
22 views

Guarantee Period - standard deviation and mean given

I need some assistance regarding 1.2. Please can you advise whats the best solution? I seem to have worked out 1.1. The life span of an imported brand of kettles sold by an appliance giant is ...
2
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0answers
16 views

Bootstrapping A Mean: What is the significance (if any) of a converging mean for n iterations?

I have a stochastic signal, and I'm taking its mean in the canonical way and comparing that with a bootstrapped mean: ...
0
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1answer
10 views

Size of Mean Squared Error (MSE)

Is there a rule or a scale for judging if a certain MSE is small, very small, big or very big? Please give also a source to underpin your recommendation.
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0answers
39 views

Is this sample drawn from the normal distribution ? using information from both mean and standard deviation

After correcting for a bug in my code in a previous question, I could simulate efficiently thousands of samples from the normal distribution N(0,1). I calculated the mean and standard deviation of ...
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0answers
27 views

Is the sample mean a better point estimate of the population median than the sample median?

A beginner's question to check I've understood correctly. A basic stats textbook says: "The variance of the sampling distribution of the median is greater than that of the sampling distribution of ...
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0answers
18 views

Root Mean Square Value Contribution

I have the following values: 0.157,-0.345,0.183,0.445,0.348,-0.302,-0.074,-0.054,0.113,0.251. Each of these values is the result of a subtraction between a measured height value and an interpolated ...
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0answers
8 views

Collapse FDR value of probes detecting the same gene

I'm very new in Microarray analysis, so I hope my question wouldn't be too irritating to you all. I have pre-processed and filtered my microarray datasets and perform differential expression analysis. ...
0
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0answers
12 views

Weibull survival scale notation and gamma function

I plotted a Weibull survival curve with scale parameter (0.171) and shape parameter (0.91) for which I now want to calculate the mean and SEM (from the variance). My question is the scale parameter ...
0
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0answers
16 views

Which model shall I use, and do fitting in “Two-stage Estimator”?

After I have estimated the means and variances of errors. How to implement the two-stage estimator by machine learning? Shall I separate the target items from training set and testing set? If I ...
0
votes
1answer
66 views

Interpreting Coefficients of a Linear Model

I'm having difficulty in interpreting the results of a linear model. I have two categorical: States (AK, IL, MO, KS) and Roads (Con, Cem, Mud) and one continuous predictor variable (Days). My response ...
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0answers
44 views

Descriptive formula for the mean of a discrete frequency distribution

I'm trying to typeset a formula for an R expression that determines the mean value from discrete distribution data. Here's some example data to describe my question. ...
4
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3answers
207 views

Sensitivity of the mean to outliers

Is the mean sensitive to the presence of outliers? I initially thought it wasn't, because a small amount of observations shouldn't have much impact, but was told that since those observations have ...
6
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5answers
209 views

Explaining Mean, Median, Mode in Layman's Terms

How would you explain the concept of mean, median, and mode of a list of numbers and why they are important to somebody with only basic arithmetic skills? Let's not mention skewness, CLT, central ...
4
votes
1answer
117 views

Does the first principal component differ from simply computing the mean of all variables?

I was just wondering if the first principal component, while I am trying to find it for a dataset of 18 variables, is different from simply adding all variables and finding the mean? I.e. to compute ...
3
votes
1answer
52 views

How do I find the standard deviation of the difference between two means?

I have two means and two standard deviations: M = 45.11, SD = 14.21 M = 60.11, SD = 14.36 I know to calculate the difference in means I can take one from the other, but how do I calculate the ...
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0answers
14 views

Expression for the expectation of joint bivariate binomial random variables

I am working with pairs of variables, $x_i$ and $x_j$ from $x_1,\ldots,x_k$ that follow a multinomial distribution with $k$ variables, $N$ trials and probabilities $p_1, p_2, \ldots, p_k$. If I work ...
4
votes
2answers
85 views

Best way to report mean±SD of p-values (all values are positive and SD is larger than the mean)

I have 50 p-values. I want to show the mean of these 50 and the standard deviation: 0.06 ± 0.19 The standard deviation is quite large, because although almost ...
1
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1answer
37 views

Calculate standard deviation when subtracting and dividing means

I have a series of independent uptake rate (u) measurements at different times (2h, 4h, 6h, 24h) (n=3) and want to find the difference between the mean values for each time with standard deviation. ...
3
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0answers
25 views

Compare two population means at different time point

I am trying to determine the change in the size of a population during a 20 year period using two scenarios. I run the model for each scenario 100 times under different random seeds and then take the ...
0
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1answer
30 views

What do the angular parentheses in $\langle g_n \rangle^2$ mean?

I am reading this paper. At the first part it says $\langle g_n \rangle=0$ and $\langle g_{n} \rangle ^2=1$. I know that $\langle x \rangle$ is used in physics to refer to the mean. So, the second ...
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1answer
37 views

Clustering using using min,max,mean and standard deviation

I have read some papers on clustering application to detect outliers in the data set. In many places the ...
1
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1answer
27 views

Denominator for mean and standard deviation of salary: the number of people or the number in work?

I am contacting recent graduates and trying to find out how much are they earning. However, there are unemployed graduates. So when I calculate the mean salary or standard deviation of our graduates, ...
1
vote
1answer
25 views

Mean value of a (portion of an) exponential distribution satisfying a given inequality

I have some questions about exponential distributions. I have tried googling around but with no success. Imagine we have an HTTP server which serves Web pages in $x$ milliseconds, with a mean ...
2
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0answers
45 views

Types of Mean in statistics

Can anyone explain trimmed mean, interquartile mean and trimean with examples? And also explain what is the use of this and where we use in real life?
0
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1answer
18 views

Calculate Forecast Error: Different ways using the mean?

Example: I've got an forecast with 2000 values. Let's say they are for one year. I can group my values into months. Every month can include a different number of single values. (JAN with 200 values + ...
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0answers
32 views

geometric mean and the normal distribution

If you have data that are sampled from a normal distribution, what is the relationship between the arithmetic and geometric means? Would it ever make sense to report the geometric mean instead of the ...
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0answers
13 views

Mean value data [duplicate]

Can I get the mean from incoming data values? I understand that I can calculate the mean of a sequence of values, but that means that I have to keep every value until the end, and then calculate the ...