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

learn more… | top users | synonyms

-1
votes
0answers
18 views

How to find the distribution of a function?

How would one go about solving the following question: Assuming that $X \sim \mathcal{N} (μ,σ^2)$, find the distribution of $\sqrt{n}(\hat{\mu} - \mu)/σ$
-2
votes
1answer
17 views

What is the Mean Squared Error for this estimator?

I understand that to find the MSE, i must find the variance and bias and add them together. I've had trouble calculating either of these so a breakdown would be immensely helpful. The estimator is: ...
1
vote
2answers
28 views

The meaning of scale and location in the Pearson correlation context

According to wikipedia, pearson correlation is scale and location invariant. Does scale refer to "variance" and location refer to "mean" ? Thanks.
0
votes
0answers
14 views

Create a histogram with mean and stddev [on hold]

I have such a set of data to create a histogram in frontend. ...
1
vote
2answers
24 views

How should I determine an average from a set of averages

I have a set of lines. I measure their length each 5 times, and then take the mean of their lengths (as I measure them). I also take the standard deviation. I want to know the 'average' line length. ...
0
votes
0answers
42 views

mean of log or log of mean

I'm interested in how indiviudals are influenced, by other individuals they are connected to. So mean values of connected individuals are included in a linar regression model. Some of my variables are ...
2
votes
1answer
44 views

Distributions with Median=Mode=Average?

Is there any important distribution with Median=Mode=Mean, apart from the Gaussian and Student's distribution?
0
votes
1answer
30 views

Trimmed mean vs median

I have a data set with all the calls made to an emergency service and the response times of the ambulance department. They admitted that there are some mistakes with the response times as there are ...
0
votes
1answer
19 views

How to compare the means of two populations that were subject to five treatments?

I have two populations that were each subject to 5 different treatments and I want to compare their means. This sounds like a great problem for multiple confidence intervals, but I don't want to make ...
1
vote
1answer
25 views

SPSS ANOVA or MANOVA or huh?

Me again asking the silly questions - this might belong here as I've been told it may belong in a software section somewhere..? Which I have still been unable to find. Here is a screenshot of my ...
0
votes
1answer
17 views

What key information should one report regarding this table? [closed]

I am unsure of what key findings to report from this table.
-2
votes
0answers
18 views

What does this table tell me? [closed]

I am wondering if someone could help me with determining what you learn from looking at this table.
5
votes
2answers
79 views

Can the difference between the means of two groups lie outside the confidence interval for the difference?

I received this question from a colleague which left me with a desire to find out a bit more about it. If you have two groups A and B with means--for example, 7.9 and 5.8--is it possible that the ...
0
votes
0answers
13 views

R limma voom function trend in mean-variancerelationship

I am new to the Limma package and when using voom I get this. I am really not sure what it means. I wonder if anyone here have seen something like this before, or ...
0
votes
1answer
27 views

Question about probability of 0.99 that an average lies less than L years above overall mean

The duration of Alzheimer’s disease, from the onset of symptoms until death, ranges from 3 to 20 years, with a mean of 8 years and a standard deviation of 4 years. The administrator of a large medical ...
1
vote
1answer
32 views

Beta binomial mean different from actual mean

I have data that I am fitting a beta binomial distribution to. The VGAM package for R is being used to do this. However, the the mean of the fitting beta binomial distribution is vastly different from ...
0
votes
0answers
6 views

Calculating average fuel consumption with no complete data

Background I just answered a question about SQL on StackOverflow, but think there's a more important question about statistics which I'm unqualified to answer. The asker has 3 fields: f - Fuel ...
1
vote
0answers
17 views

Calculating the highest of overlapping sets

My data set looks like the following: I have information about a large number of devices. For each device, I also have the data consumed by an application per day. Note however, all the devices ...
0
votes
0answers
8 views

Choosing the right bins - 2d to 1d radial average with correlations

I have a 2d array of data. I want to take the average of the values in radial bins, the average is dependent on radial distance (Basically dealing with the 2d Power Spectral Density from and Image and ...
15
votes
6answers
420 views

Is the median a type of mean, for some generalization of “mean”?

The concept of "mean" roams far wider than the traditional arithmetic mean; does it stretch so far as to include the median? By analogy, $$ \text{raw data} \overset{\text{id}}{\longrightarrow} ...
1
vote
0answers
24 views

Reporting Results of Mann-Whitney U Test - Means vs Medians

I had a question yesterday that I got a bunch of great responses on. I have, hopefully, a quicker question here. There is a debate in the literature regarding reporting means vs medians in a ...
1
vote
1answer
100 views

2 discrete distributions with equal mean and variance

I need to compute 2 discrete distributions with equal mean and variance. One should be a distribution taking values x and y and the other one taking values z, 0, and y. The probabilities should take ...
7
votes
1answer
581 views

Which converges faster, mean or median?

If I draw i.i.d. variables from N(0,1), will the mean or the median converge faster? How much faster? To be more specific, let $x_1, x_2, \ldots $ be a sequence of i.i.d. variables drawn from ...
3
votes
2answers
86 views

How to properly state the average of a discrete number in a report?

I'm wording a report on the averages of a discrete variable, and am trying to get the most appropriate sounding wording. Consider the able below: ...
6
votes
1answer
161 views

Displaying Ordinal Data - Means, Medians, and Mean Ranks

Thanks in advance for any help. I have some ordinal data that is not normally distributed, so I decided to do non-parametric testing using the Mann-Whitney U Test. I am looking at differences ...
-3
votes
1answer
76 views

Calculating mean and variance of normal distribution restricted to interval

If one set a lower and an upper limit on the normal density, is it statistically valid to calculate the mean and Standard deviation of that normal variate. If yes, how can we do that in R? In a more ...
1
vote
0answers
27 views

Generate discrete distributions with same mean and variance

I have a question concerning mean-variance analysis. I need to compute 2 discrete distributions with equal mean and variance. One should be a distribution taking values x and y and the other one ...
4
votes
1answer
28 views

Is this method of arriving at a statistic valid?

The following is an excerpt from an article about gender bias : Overall, 34 per cent of respondents readily admitted that their family preferred having more boys. Given the sensitive nature of ...
0
votes
0answers
15 views

Calculate mean of several tetrachoric correlation coefficients

how do I calculate the mean of several tetrachoric correlation coefficients? Do I have to use Fisher's z transformation before? Thank you
0
votes
0answers
27 views

Gaussian or Dirichlet Process from aggregated samples

For N individuals, I have the number of measurements taken per individual, the individual's mean measurement value, and the standard deviation of the individual's measurements, but I do not have ...
2
votes
2answers
66 views

Mean Preserving PDF Spreading

I have a histogram representing the PDF of an unknown discrete RV. The histogram is asymmetrical. To be clear, all I have is the histogram. Is there a known way to increase/decrease the variance of ...
1
vote
0answers
26 views

Mulitvariate normal truncated conditional expectation

There is three-variable multivariate normal distribution. Denote 3 variables with $X_1$, $X_2$, $X_3$. Let $\mu_i$ be means, and $\sigma_i^2$ variances of respective variables, and let $\Sigma$ be ...
0
votes
1answer
29 views

Find new mean from Normal probability

I have a problem as follows. Life of tyres normally distributed for a specific make. mean=24,000 km and sd= 2500 km. Question is: As a result of improvements in manufacture, the length of life is ...
1
vote
1answer
26 views

Compare means of group with a mean of a subgroup

It is possible to compare a variable, for example age, between an entire group of patients and a subgroup of patients (a part of the entire group)?
5
votes
2answers
141 views

Arithmetic or geometric mean to calculate an annual average price index?

I have monthly indices (Consumer Price Indices for 12 months) for a set of countries. I want to calculate the annual average for each country in order to have an average Consumer Price Index for a ...
1
vote
1answer
32 views

Comparison of two means within the same group

I created a pretest before my main study. The goal of the pretest is to find two brands that are equal in terms of liking and familiarity. I computed the variables in SPSS and I was wondering if I ...
1
vote
0answers
23 views

Should I use arithmetic or geometric mean here?

So I have monthly indices (Consumer Price Indices for 12 months) for a given country. I want to calculate the annual average for each country in order to have an average Consumer Price Index for a ...
1
vote
0answers
23 views

Suitable model for predicting mean output over time

I have 3 years of yearly historic data on the results of a harvest (of truffles) from multiple different areas involving multiple individuals harvesting in each area. The dataset contains: name of ...
2
votes
1answer
50 views

Can covariance be derived from means and variances?

In treatment studies it is common to report multiple outcome measures from the same subjects. The treatment effects on these outcomes are typically correlated so this should be taken into account ...
1
vote
0answers
17 views

Relationship between mean and variance not removed after data transformation?

I am a student and I am doing a research where I have a trait (lets say cow weight in kilograms) that presents a relationship between mean and variance. I also have a factor that is country/year ...
-2
votes
1answer
27 views

Is the mean smaller than the median

The mean and the median selling prices of single-family homes were reported to be \$163,900 and \$210,900. The report was not clear about which was which. \$163,900 is the mean and \$210,900 is the ...
4
votes
2answers
82 views

Finding the Mean and Variance from PDF

A random variable $n$ can be represented by its PDF $$p(n) = \frac{(\theta - 1) y^{\theta-1} n}{ (n^2 + y^2)^{(\theta+1)/2}}.$$ $\theta$ is a positive integer and $y$ is a positive parameter. If ...
0
votes
0answers
52 views

Bootstrapping with standard deviation, mean and autocorrelation

I found in the matlab examples a way to use mean and sd for bootstrapping: ...
1
vote
2answers
29 views

Will the mean of a set of means always be the same as the mean obtained from the entire set of raw data?

If I have calculated the mean for 4 data sets (which do have different sample sizes), can I then obtain an "overall mean" by calculating the "mean of the means"? If yes, will this "mean of the means" ...
3
votes
3answers
174 views

The probability of a random variable being larger than a sequence of random values

Suppose we have a fixed, known, $n$, and each $x_1 \ldots x_n$ is a random number generated uniformly over $[0,1]$. What is the probability that $x_n$ is the largest value in the sequence?
0
votes
0answers
23 views

Do I need to use weighted means with the Wilcoxon signed rank test?

I have 22 patients. They have been measured pre and post treatment. There are 3 measurements per patient before treatment (pre baseline), and four measurements after treatment (post baseline). There ...
3
votes
2answers
140 views

Are there any other distributions whose shapes can be determined by just the mean and the standard deviation?

For the normal distribution, With the mean, and the standard deviation, we know the shape of the specific normal distribution - that is, the center of it and how spread out it is. I wonder if there ...
2
votes
2answers
73 views

Standardize non-normal predictors before performing binomial GLMM using mean and sd?

I am planning to predict a binomial variable (1/0, a used point by an animal or point available to an animal in its range) using several continuous, distance-based predictor variables (distance to ...
2
votes
0answers
53 views

If $Var[X]$ is much larger than $E[X]^2$ is E[X] an unreliable estimate?

My question is simple and I got this confusion when going through a Markov chains text book.If $Var[X]$ is much larger than $E[X]^2$ is $E[X]$ an unreliable estimate?
2
votes
1answer
66 views

Is my sample homogeneous? [closed]

I have a sample of 110 values between 0 and 180. These represent total degrees in an arc, and I want to be able to figure out whether or not I have a widely variable sample of arc sizes or if I have a ...