# Questions tagged [z-statistic]

The statistic used in z-test, namely the ratio of a parameter estimate and its estimated standard error.

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### Does it make sense to report the median (not mean) of z-scores?

I have a set of z-scores that I acquired from my computer simulations. These z-scores pertain to the experimental results under a specific setting (let's call this setting ...
22 views

### Should we always calculate the z in a confidence interval as 1 - (alpha/2)?

I'm currently beginning my studies in statistics and all of the examples of confidence interval questions I studied used (let's assume a 95% confidence interval) as a z formula ...
56 views

### This function can get p-value from which statistics?

I know that I can get p-value from z-statistic (called zval here) using following function (Python): pval = 2*(scipy.stats.norm.sf(abs(zval))) or with: ...
26 views

### Digital Product A/B Testing: Z vs T test

I'm a beginner in statistics. When it comes to digital product A/B testing, I'm told by my company's analyst that they typically use the T-test for the hypothesis testing Why would we not use the Z-...
76 views

### What does it mean if Z statistic is -Inf?

I have ran a Wilcoxon rank sum test to compare two independent samples. I now want to get a Z statistic to report, but when I do so, it results in -Inf. What does ...
380 views

### Eta-squared from Kruskal-Wallis in R

Is it possible to calculate Eta-squared from Kruskal-Wallis test results? I know how to do it by hand for the ANOVA or Mann-Whitney using the Z-statistics, but i must use the KW test for my current ...
50 views

### Why does the pivotal quantity $g(X,θ)$ have to be a monotonic function of $θ$ for a fixed $X$?

I'm learning about pivotal quantities, which are functions $g(X,θ)$ of the data $X$ and the parameter $θ$. One property they must satisfy is that $g(X,θ)$ is a monotonic function of $θ$ for a fixed $X$...
86 views

### Standard deviation Vs ٍٍStandard error

I'm little bit confused, when I want to standardize a normal distribution, when to use standard error and when to use standard deviation ?. In statistics we often use samples so, is it always we use ...
### Using the $Z$-test instead of the binomial test for small $n$ - effect on power and Type I error
Setup Let $M \sim \text{Bin}(p,n)$. Let us then state the following two hypotheses: \begin{align} H_0: p = 0.5 \text{ vs } H_1: p > 0.5 \end{align} To test these hypotheses, I could use the ...