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

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10 views

Multiple DVs - MANOVA or multiple ANOVAs?

My project has multiple continuous DVs and a single categorical IV. When I run ANOVA for each of my DVs the means and SDs are different to when I use MANOVA. Why is that? Which one is correct? Which ...
2
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1answer
59 views

How can I recreate a Weibull distribution given mean and standard deviation and the shape and scale parameters are unknown?

Figure 2 is a Weibull distribution of three different wind farms in Canada. These 3 probability distributions were combined in a study to obtain a common wind speed model. I will be using this common ...
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14 views

Comparing two data sets for a trend in the data

I have two data sets ( have only access to the statistics of data sets like mean, percentile, count etc but not the data it self). I am interested if I could have a metric which can answer below ...
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0answers
5 views

mean and standard deviation of a population [on hold]

you are given a sample of a temperature in one month in the city over the past hundred and thirty years. three days it was 50 to 59 degrees 307 days it was 60 to 69 degrees 1439 days it was 70 to 79 ...
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12 views

Regarding Bootstrap Hypothesis Test for difference of means, why not absolute differences?

Looking at the Algorithm 16.2 from "Introduction to the Bootstrap, Efron and Tibshirani" I was wondering why isn't the t(.) being tested the absolute difference of the means, instead of the ...
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2answers
41 views

Best way to test that one mean is greater than all the others

Suppose I have $k$ samples of different sizes, each of a different univariate variable. I want to test the significance of the hypothesis that the population of $k_0$ has a mean greater than all of ...
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1answer
10 views

Harmonic mean for averaging predictions?

I have 14 different predictions about each observation in my dataset and I want to compute an overall prediction for each observation based on these. Would it be better to use the harmonic mean ...
2
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1answer
37 views
+50

Transformation among power-means

It is well-known that arithmetic and geometric mean are strongly related via logarithmic transformation, i.e. if we take arithmetic mean of logarithmic-transformed values we get the same as if we take ...
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0answers
5 views

Comparing Variance Ratio tests to Hurst exponents

I have used the Chow Denning test and the Hurst exponent (Peng, Whittle and R/S methods) to examine if a particular time series follows a random walk. My results are conflicting between the 2 tests. ...
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19 views

Plotting cumulative average means in ggplot2 [closed]

I want to depict the result of several replications (mean, confidence interval) ...
3
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3answers
105 views

How large does a Poisson distribution's mean need to be to use normal distribution statistics?

As the mean of a Poisson distribution increases, the Poisson distribution approximates a normal distribution. I assume that once the Poisson mean becomes large enough, we can use normal distribution ...
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0answers
13 views

Significance of excess return using geometric mean

Since I am writting an assignement about a contrarian-strategy I have to test if the excess returns are significant or not. I calculated the excess returns this way: geomean(pf_returns) - ...
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1answer
24 views

Why is it necessary to divide by the number of samples when optimizing squared error?

In a lot of different optimization problems, and with particular regard to gradient descent, we use the mean squared error as a loss function. In the formulation of mean squared error, you divide by ...
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2answers
283 views

Calculating SD for normal distribution with only mean and 5% and 95% quantile values

As part of a Bayesian method to estimate the divergence times of species, priors have to be set with values based on previous literature or known fossil dates. These priors can have different ...
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1answer
12 views

Coefficient of determination applied to difference in means?

Assume we have one random variable X, and two groups A and B have different mean X values. Let's say we have another variable Y that has a correlation with X of 0.5. If I wanted to estimate a Y ...
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0answers
35 views

Correlation between two samples of different size

I have all price quotes from a stock (to be more precisely CSAN3 from Ibovespa Exchange - Brazil) from 2010 to 2015. I was asked to get the correlation from the log returns year-by-year. This is ...
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2answers
53 views

How to calculate mean, median, mode, std dev from distribution

How to calculate mean, variance, median, standard deviation and modus from distribution? If I randomly generate numbers which forms the normal distribution I've specified the mean as ...
28
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3answers
3k views

What can we say about population mean from a sample size of 1?

I am wondering what we can say, if anything, about the population mean, $\mu$ when all I have is one measurement, $y_1$ (sample size of 1). Obviously, we'd love to have more measurements, but we ...
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1answer
32 views

How accurate is my simple description of a confidence interval?

Here's my simple words-only description of a 95% confidence interval for the mean. How accurate is it? the sample mean comes from a distribution of possible sample means the sample mean might have ...
2
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1answer
25 views

Comparing means of 3 dependent percentages

This is an example of the data that I have. 30 plants are a sample. Each plant has been categorized as percentage of green, brown or yellow color (percentages per plant sum to 100). For example: ...
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0answers
15 views

Relation between bootstrap mean and parameter value estimated via maximum likelihood

I have an observed data set $O$ and a synthetic model $S(\theta)$ which attempts to describe it. By fixing $\theta$ to different values I can generate $M$ synthetic realizations of the model: $$S_k ...
2
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1answer
52 views

Method of meta-analysis of studies to determine mean blood level

Generally meta-analysis is done to determine the efficacy of some treatment as compared to controls. Is it possible to do a meta-analysis of different studies for mean blood level of a chemical, its ...
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0answers
21 views

Should I use a composite standard deviation for these multiple biological/technical replicates?

I used an ELISA to determine protein concentration from absorbance readings, which is a nonlinear relationship. I have 3 sample types, which are broken down into 3 biological replicates (per sample), ...
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23 views

Alerting framework for incoming traffic using mean or standard deviation

Currently I put hourly traffic (total number of input requests) of my website in a MySQL table. I keep data for the last 90 days. I want to check every hour, lets say 6th hour, that whether the ...
3
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1answer
74 views

How to select the 'best' trim value for the mean function?

I'm experimenting with the trim parameter to the mean function, E.g. ...
4
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1answer
66 views

Estimating the mean of a variable by controlling for age etc.: Why using median values?

just read this thread here (How do I estimate the mean of a variable for different groups by controlling for age, gender, education...?) and found it very helpful! First of all, thanks for that to the ...
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29 views

Can we use normal distribution statistics on frequency distribution outputted by bootstrapping?

If I understand correctly, this is the bootstrapping procedure: Pretend sample is population Repeatedly resample from this pretend-population Calculate the mean of each resample. The output of ...
3
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1answer
55 views

How often will sampling distribution of the mean not be normally distributed?

Kabacoff 2015 suggests that if we're not willing to assume the sampling distribution of the mean is normally distributed, we should use bootstrapping to estimate the sampling distribution of the mean. ...
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12 views

Estimate variance from multiple distribution

Suppose I have $N$ feature vector and for each feature I have calculated the mean and variance. Now suppose I concatenate all the feature vector (appending one behind the other) and now if I want to ...
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1answer
49 views

How to compare means in two or more variables?

I am a newbie in statistical analysis and trying to figure out way(s) to compare means in different variables. I have three variables (seven point likert type data but allowed to treat as scale) ...
3
votes
1answer
62 views

Testing Sharpe Ratio significance

What is the proper way to test the significance of Sharpe Ratios or Information Ratios? The Sharpe Ratios will be based on various equity indices and may have variable look-back periods. One solution ...
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0answers
8 views

Developing Regression equations using factors both as independent and dependent variable

I am doing research on automated banking service quality. In my work I have found in total 6 dimensions (factors)....4 service quality(SQ) factors,1 customer satisfaction(CS) factor and 1 loyalty ...
1
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1answer
36 views

Standard deviation of a casino's profit

For the following question, I've determined the mean to be \$0.20, but how do I determine the standard deviation? A slot machine at a casino pays out an average of \$0.9, with a standard ...
5
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1answer
97 views

On the sample complexity of mean estimation in $\ell_p$-norm

Let $1\leq p\leq \infty$, let ${\cal D}$ be a distribution over $\mathbb{R}^d$, and assume its support is contained in the unit $p$-ball. What is the minimum number $n$ of i.i.d. samples $W_i\sim ...
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2answers
64 views

When using SVMs, why do I need to scale the features?

According to the documentation of the StandardScaler object in scikit-learn: For instance many elements used in the objective function of a learning algorithm (such as the RBF kernel of Support ...
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0answers
19 views

How to compute the average of the relative weightings?

I have the following problem. I have a sample of daily snapshots of a portfolio grouped by four asset classes: Forex, Futures, Options and Equities. For each day in my sample I compute the weight of ...
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1answer
46 views

Understanding “the kernel has zero mean”

I am trying to understand kernel density estimation and found the graphic below illustrating different kernel functions on Wikipedia. I have no trouble reconciling it with the two statements "the ...
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0answers
57 views

Confidence interval of the mean for a beta distribution when alpha and beta are estimated [duplicate]

I have elementary knowledge in statistics. I'm trying to estimate the confidence interval for mean of a beta distribution as specified in this article using log likelihood estimation given alpha, beta ...
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0answers
60 views

threshold based on mean and standard deviation

I have a time series of 70000 data points. I want to separate samples of this time series which have very large values as compared to the time series. How can i threshold sample to separate. What i ...
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1answer
30 views

Comparing mean differences between groups when standard deviation in one of them is 0

I was wondering if it is possible and -if yes- what are the implications when one is trying to compare mean group differences of a continuous variable that varies in one group but is a constant number ...
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1answer
37 views

AUC per time is nothing else than the mean?

Using AUC is in vogue and has found his place also in clinical research (example). What I don't understand is AUC per time. For example, if a clinical or psychological parameter is measured over time. ...
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1answer
24 views

Statistic test when bias is not random

Is there a statistical test that I can use to say that there is bias in the result of my analysis but the bias only occurs at certain region. The scatter plot below probably will make more sense: ...
5
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2answers
73 views

Independence of Sample mean and Sample range of Normal Distribution

Let $X_1,\dots,X_n$ be i.i.d. random variables with $X_1 \sim N(\mu,\sigma^2)$. Let $\bar X =\sum_{i=1}^n X_i/n$ and $R = X_{(n)}-X_{(1)}$, where $X_{(i)}$ is the $i$ the order statistic. Show that ...
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43 views

How do I solve this problem? Novice here

Here's the problem. I work for a transportation company and we're trying to prove the following hypothesis: Drivers are allowing passengers on the vessel without taking taking their paper boarding ...
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0answers
58 views

How to plot mean plus/minus standard deviation for histograms?

I have a set of grayscale images, where the pixels may have values in the range $[0, 255]$. From each image, I calculate a histogram, which shows how many pixels have the value $0$, $1$, $2$, and so ...
9
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1answer
398 views

Is the median a “metric” or a “topological” property?

I apologize for the slight abuse of terminology; I hope it will become clear what I mean below. Consider a random variable $X$. Both the mean and the median can be characterized by an optimality ...
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0answers
58 views

How to calculate mean and standard deviation of a range variable (grades) when the raw data is based on frequency categories?

Results of an exam indicate that: 13% of the class earned an A 20% earned a B 48% earned a C 10% earned a D 9% earned F's The grade C ranges from 70-79%. Assuming that the data is normally ...
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3answers
46 views

How many samples needed to approximate true mean?

If I have some arbitrary random variable with true mean $\mu$ how many samples from its distribution do I need to take such that the empirical mean $x$ approximates $\mu$ within an error of less than ...
6
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1answer
146 views

Efficient way to compute distances between centroids from distance matrix

Let us have square symmetric matrix of squared euclidean distances $\bf D$ between $n$ points and vector lengthed $n$ indicating cluster or group membership ($k$ clusters) of the points; a cluster may ...
0
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1answer
57 views

Making the most of Standard Deviation and P value — graphing?

I have a question or two in regard to getting the most out of the statistics of my data. By way of background, my qualitative observations of two distinct populations that are uniformly regarded to be ...