# Questions tagged [mean]

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

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### 5 vs 3 measurments of one parameter

Hellow, smart people of the internet, I have a question: We are doing a study of 170 people- where 20 parameters will be measured 3 times over 2years and the median of every parameter will be compared ...
228 views

### Estimating mean and SD given the median and IQR values

it is possible to estimate mean and SD given the median and IQR? I am involved in a meta-analysis where some trials show outcomes as mean and standard deviation but most show median and inter-quantile ...
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### Is there an easy way to mentally calculate mean an variance? [closed]

Giving a generic numerical data is there an easy way to calculate mean an variance mentally or at least some easy formula that minimize the error with the correct mean and variance?
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### Confidence interval for the sum of 2 binomially distributed variables

$P_1$ and $P_2$ are uncorrelated, binomially distributed variables with success probabilities $p_1 \neq p_2$. Say I measure: $k_1 = 9$ successes out of $n_1 = 10$ trials for $P_1$ and $k_2 = 1000$ ...
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### $\mathbb{E}[X^2]\leq k \mathbb{E}[X]^2$, upper bound second moment from first moment

Let $X$ be a non-negative random variable bounded on $[0,1]$. Is it true that $\mathbb{E}[X^2]\leq k \mathbb{E}[X]^2$ for some constant $k$? If not, are there any minimal assumptions on $X$ where this ...
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1 vote
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### Conditional and unconditional mean in GARCH(1,1) model

Say I have a stationary time series and want to fit a GARCH(1,1) model. Does this mean that the conditional mean, which is used in GARCH, would always be the same as the unconditional mean of the ...
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1 vote
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### Can raw means and estimated marginal means be the same ? And when?

I have read a lot about calculating raw (standard) means and EMM. First are data based (descriptive stats), the latter are model based. I try to learn how to calculate both of them. In my example both ...
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### Why is taking the mean RMSE sometimes so far off overall RMSE?

I'm working with a multi-threaded program, which splits a dataset into N chunks, and evaluates some regression model's performance, predicting a score for each item in each chunk. I'm using RMSD as ...
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### compare means of lognormal distribution

I have a small set of data that I used to generated a lognormal distribution: ...
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### Can I compare two estimates by their sample variance?

For example, to estimate the population mean $\mu$, I am given two sample mean $\bar{x}_1$ and $\bar{x}_2$ from two (independent) data sets of $N_1$ and $N_2$ observations respectively. Without access ...
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1 vote
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### Confirming my calculation of mean, standard deviation and median for a histogram

Average travel time* for men = 27.2 minutes, women = 23.6 minutes My calculations are the followings: The problem is my calculated mean is 28.4 but chart says 27.2 I calculate the mean with this ...
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### Can ANOVAs or Student tests be conducted on any summary statistic at the individual level?

I am wondering if ANOVAs or Student tests can be performed on any summary statistic of performance at the individual level without any effect on type 1 and type 2 error. For example, consider a simple ...
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### How does a Random Sample relate to Random Processes and Random Variables?

What is the difference between a Random Sample, Random Variable (RV) and Random Process (RP)? As far as I know, a RV is a mapping from an experimental space to the real numbers and a RP is a mapping ...
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### Comparing ratios of independent means by calculating SE difference – applicable?

I am conducting a study comparing the ratio of a mean number of vocalizations to the mean number of individuals across three treatments. For each treatment, I have the mean number of vocalizations (...
1 vote
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### General Expression for the $t$-th difference of conditional means

In econometrics, it is common to work with the difference-in-differences of conditional means. For example, let $Y$ denote a variable of interest and $X_{1}$ and $X_{2}$ denote binary regressors. The ...
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### What do I do when I *want* to accept the usual null hypothesis?

I have samples from two random variables, and I'm assuming normal distribution with equal variance. I want to show that the distributions have equal means $\mu_1$ and $\mu_2$. The usual two-tailed t-...
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### Is this ratio between sum of squares beta distributed?

Consider $x_i \sim N(\mu,\sigma)$ I am interested in distribution of the the following statistic (arises from likelyhood ratio test):  \frac{ \sum_{n=1}^{n} (x_i - \overline{x})^2 }{ \sum_{n=1}^{n} (...
1 vote
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### Box plots of monthly averaged water flow

I am working with a model that models water flows in a certain area. These flows can be influenced by taking certain measures, resulting in multiple water management scenarios. I would like to compare ...
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