Questions tagged [mean]
The expected value of a random variable; or a location measure for a sample.
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examine the differences in outcome according to the variables ( with a boxplot and significance level )
My participants ranked their experience (-1, 0, 1) from 4 different perspectives (Overall, Usability, Effectiveness, and Visual design which I call variables). Finally, they specified if their usage ...
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1answer
11 views
How do I find population mean μ for a value that has uncertainty
I have a value x = 60 ± 5.5, and I want to find the population mean μ_x (mean of x), and the population variance of x. How can I do do this?
Sorry for the noob question, but I've spent 3 hours trying ...
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10 views
Aggregating (taking the mean of) a censored variable
This post is related to this post.
I have survey data, with a (censored) range from 0-100, that looks as follows:
...
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13 views
Random variable with finite logarithmic first moment, infinite logarithmic variance [duplicate]
Could you provide an example of a random variable $X$ such that $|\mathbb{E}(\ln(X))|<\infty$ but $\text{Var}(\ln(X))=\infty$, if such a random variable exists at all?
Related: "Random ...
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Random variable with finite exponential first moment, infinite exponential variance [duplicate]
Could you provide an example of a random variable $X$ such that $\mathbb{E}(e^X)<\infty$ but $\text{Var}(e^X)=\infty$?
Related: "Random variable with finite logarithmic first moment, infinite ...
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Attempting to create a table in R that shows the mean and sd for stock prices of companies in each sector [migrated]
I have financial data (CleanStocks.csv) that include sectors, companies, and their stock prices. I needed to find out find how many companies were in each sector so I did ...
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26 views
Convergence in distribution versus convergence of moments
Suppose we have that a random variable sequence $(X_n)_n$ converges in distribution to a law with mean $\bar{\mu}$ and variance $\bar{\sigma}^2$, or formally $X_n \stackrel{d}{\to} \mathcal{L}(\bar{\...
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1answer
84 views
Can a P-value be calculated with these 4 statistics?
This is all you know.
There are two farming plots, they are adjacent to each other, with the same soil type and irrigation methods. Yields for the two plots are available for 15 years.
Plot 1 has an ...
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23 views
Mean number of throws to exceed a threshold [duplicate]
Say that you have a die with n faces, and you need to throw the die until the sum of your results exceeds a given threshold.
What is the average number of throws needed?
I think that to compute that ...
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13 views
How to compare means from a CLT exercise and a Normal distribution if i have n=4896 random samples
i have the central limit theorem exercise solved but the normal distribution not.
i want to compare the means and now i am stucked.
the exercise is a discrete random variable modelling in a table with ...
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16 views
How to calculate the percentage of change between two dates without being fooled by trend effects?
I have a dataframe of sales per store and per item between month 0 and month 33, these sales represent a non-stationary time series. I want to calculate how much these sales are increasing. But I don'...
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245 views
How to estimate $P(x\le0)$ from $n$ samples of $x$?
Suppose, we have $n$ samples $x_i$ of a random variable:
$$x \sim \mathcal N(\mu,\sigma^2) $$
Based on the samples, we want to estimate the probability that $x$ is negative:
$$P(x\le0)$$
Intuitively, ...
1
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1answer
60 views
Probability of sample mean
Consider independent random variables $Z_{i}\sim N(0,1),\;i=1,\ldots,16$
and let $\bar{Z}$ be the sample mean. Then calculate $P\left[Z_1-Z_2<2\right]$
This is an example of one of the ...
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0answers
9 views
Standard Deviation calculations [duplicate]
C[Calculate the mean and standard deviation of each investment, assume that both returns come from independent samples, are both normally distributed and that the (true but unknown) variances are the ...
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37 views
Calculating MEAN and STANDARD DEVIATION confussed
[]
**
calculate the mean and standard deviation of each
investment, assume that both returns come from independent samples, are both normally
distributed and that the (true but unknown) variances are ...
2
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1answer
32 views
Mean and variance of the Gaussian resulting from Central Limit Theorem
Let $\{x_i\}$ be a set of iid random variables (not necessarily Gaussian distributed). The CLT states that $\frac{1}{n}\sum_{i=1}^n x_i$ is asymptotically normal.
What do we know about the mean and ...
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1answer
21 views
Checking significance in differences between groups (gaps in income between genders and education levels)
I wonder if you could give me a hint on how to find out whether there is a significant difference in the income gap between genders and their education level. The picture below shows education levels (...
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0answers
11 views
What analysis to use to compare means for when subjects are paired with multiple subjects?
I have 2 sets of data that are connected like below:
As you see, each ID in set 1 might be connected to at least one ID in set 2 and vice versa. My aim is to compare the values of variable B for ...
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0answers
3 views
Calculate column mean on single column in a database [migrated]
I'm trying to extract the first 50 observations from a db and then obtaining the mean for each column. I'm trying with the following code, but is not working.
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0answers
23 views
How to compute/estimate the probability of the mean value of a number of x results of a classification NN?
I use a neural network to classify the sentiment of some news articles per day, regarding a specific topic. Possible results are $[1,2,3,4,5]$ (1=very negative, ..., 5 = very positive). Using one ...
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21 views
Graph of model predictions vs observed data when testing a hypothesis
I have used mixed models to test a hypothesis and have checked residuals for normality. I was planning to graph the observed data and present it with model outputs (coefficients, p-values). However, ...
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30 views
Estimation of the mean of the autocorrelation of the time series
I have asked a similar question before, and I was encouraged to repost the question with more details. I am not all that familiar with the jargon, so feel free to edit the post or add the tags.
I ...
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7 views
How do i find if a shift in Mean is significant in two Datasets with uneven rows?
I have Two datasets with Productivity values for Two different Quarters in a year(q1,q2). Now I want to identify if the shift in mean From q1 to q2 is significant between these two datasets. Will my ...
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1answer
14 views
What is the sample size and variance for the mean that is a simple, unweighted average of two independent groups' means?
We have two groups: N1 = 10 and N2 = 100
Their means on some measurement are: Mean1 = 4 and Mean2 = 5
Their variances are Var1 = 3 and Var2 = 2.5.
Let's further assume we have no access to the ...
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1answer
13 views
Estimate a sum using proportional sampling
I have some set of items. Each item has a weight and I can sample the items from the population with probabilities proportional to their weights. I know the size of the population. I want to estimate ...
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1answer
58 views
Does one need to test independence of variables first?
Suppose one is given the following data set $X$.
"8 5 12 4 11 6 8 7 7 12 7 3 11 14 11 9 6 6 5 6 10 14 4 5 5" Let $n$ be number of data points.
One wants to obtain 95% ...
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0answers
48 views
Estimation of the mean of a long tailed distribution
I want to calculate the average of a data set in which elements are distributed according to a PDF that seems to have a quite long tail. This means that when I bin elements of this set I get a PDF ...
1
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1answer
30 views
Estimating the distribution of the maximum of N values drawn from N different normal distributions
Let's say we have N distributions $\mathcal N(\mu_i, \sigma_i)$, each with known mean $\mu_i$ and known standard deviation $\sigma_i$, $i=0,...,N-1$.
For each $i$, 1 random samples is drawn from from ...
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0answers
20 views
Averaging multiple Kendall rank correlation coefficients
How can I average multiple Kendall rank correlation coefficients?
I have found elegant solution for Pearson's/Spearman's correlations based on Fisher transformation. Am I understand correctly that I ...
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1answer
77 views
How would I compare these means correctly?
I have a data set where I want to compare the number of events that occurred in two geographic areas over a period of six years. Altogether, there are 407 districts that comprise the geographic areas.
...
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35 views
Is there a way to calculate the magnitude of the difference in means in R?
I have a dataset with a non-Gaussian distribution - signalment and body measurements of three species of bird. I have used the Kruskal-Wallis with post-hoc Dunn Test and Bonferroni correction tests to ...
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15 views
How did mdewey come up with this equation for the SE of an average of z-transformed correlations?
I have the exact same question as the OP of this thread:
I have $k$ correlations which might be based on a different N of cases. After applying Fisher's z-transformation and getting $z_{av}=\sum_{i=1}^...
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1answer
21 views
How to combine the grades of different pairs of markers?
I found myself at a difficult situation in deciding how to combine the grades of different pairs of markers such that I can rank the candidates fairly.
I have around 500 candidates and around 30 ...
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0answers
8 views
Drawing inferences from a tiny dataset on antidepressants with placebo
I have a tiny dataset about some trials for antidepressants, and I would like some help in interpreting the data. The dataset comes from here: https://dasl.datadescription.com/datafile/antidepressants/...
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1answer
345 views
Why are means not relevant to binary variables?
Trying to learn Basic Statistics from the Coursera.
At the time 29 second, the video says:
Means are not relevant with such a binary variable.
Why?
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14 views
How to use Principal Components Analysis (PCA) to find overall orientation of polygons collectively?
I was advised to use the Principal Component Analysis (PCA) to find first eigenvector which gives the direction of the first principal direction.
Principal Component Analysis (PCA) is a new concept to ...
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11 views
How to generate a series correlated to a given one, with given mean and standard deviation [duplicate]
I'm trying to generate a series Y that is correlated to series X. I know the data from X, I know the mean and the standard deviation of series Y, and I know the Pearson coefficient between X and Y (0....
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0answers
15 views
What mean use when there is outliers [duplicate]
for a project I need to get a mean each time, this mean I then use it to compare it to a distribution under the null hypothesis H0. However sometimes some values (...
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0answers
37 views
How many samples are needed to distinguish the means of two distributions?
In a paper on Multi Armed Bandits, I came across the following statement:
This generalizes the well-known fact that one needs of order $\frac{1}{\Delta^2}$ samples to differentiate the means of two ...
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2answers
59 views
Why does bootstraping not seem to produce a normal distribution for this data?
I am trying to calculate the 95% confidence interval of the mean value of the population. I have this data:
...
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1answer
24 views
Find a stardard deviation
$$N=30 \\
\sum_{i=1}^{30}x_i=120 \\
\\
\sum_{i=1}^{30}x_i^{2}=750\\
$$
Find a standard deviation of x:
$$
\bar{x}=\frac{120}{30}=4 \\
sd=\sqrt[]{\frac{\sum_{i=1}^{n}(x_i-\bar{x})^{2}}{N}}=\sqrt[]{\...
0
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1answer
24 views
Sample size for mean comparison
Suppose that I have a new machine so I want to compare it to the older one. I would like to conduct a mean comparison of a parameter, to verify if these 2 machines produce the same results or not. How ...
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0answers
25 views
Slutsky's theorem applied to a sample mean conditional on a Bernoulli variable?
Let $(Z_{i},Y_{2i})$, $i=1,2,\ldots,N$ be iid random vectors, where $Y_{2i}$ is the outcome vector and $Z_{i}\sim\operatorname{Bernoulli}(\delta)$. Assume that
$E(Y_{2i}|Z_{i})=\mu_{2}+\beta Z_{i}$ ...
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Calculating a weighted mean and weighted SD from multiple mean/SD/different sample sizes?
QUESTION EDITED:
I have 10 different patients, who have undergone heart procedures and we have collected some measurements of cardiac electrical activity from the same region of all ten hearts. Due to ...
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1answer
46 views
“Weighted average” for medians
I have data that includes ~20 groups with descriptive stats of median, count, and mean for each of the groups. I know that the means are heavily skewed, and I don't have access to the underlying data ...
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2answers
49 views
apply running median for non equidistance daily measurements with potentially several KPI measurements per day
Let us say I have daily measurements of a KPI with potential gaps (i.e. no measurements some days) and sometimes several measurements per day. How would one apply the running median (see for example ...
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1answer
24 views
Moving average (running mean) - how to keep all observations in smoothed time-series?
Let's suppose I have a time-series of 100 daily values and I want to compute a 5-day moving average of this time series.
I would do as follows:
...
0
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0answers
10 views
Sampling distribution of sum of two or more sample means [duplicate]
Let's say I have 3 sample means:
$\bar{x}$, $\bar{y}$, $\bar{z}$ with sample sizes $n_1 = n_2 = n_3$ and standard deviation $s_1$, $s_2$, $s_3$. I know how to find the distribution of the difference ...
1
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1answer
22 views
Calculate p-value for one-sample T-test in SPSS: 1 - p/2?
In SPPS, for the p-value in a one-sample T-test, 1-tailed:
When you find a mean that is in the opposite direction of your alternative hypothesis, do you have to do 1-p/2 or just p/2?
Thank you!
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1answer
30 views
Expected size of a probabilistic set
Suppose I have a set $X$ such that each element $x$ is associated with a probability $p_x$. Now suppose I build another set $Y$ from the elements in $X$ such that the probability of $x$ appearing in $...
