The statistic used in z-test, namely the ratio of a parameter estimate and its estimated standard error.
Questions tagged [z-statistic]
59 questions
62
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Wald test for logistic regression
As far as I understand the Wald test in the context of logistic regression is used to determine whether a certain predictor variable $X$ is significant or not. It rejects the null hypothesis of the corresponding coefficient being zero.
The test…
user695652
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2 answers
A/B tests: z-test vs t-test vs chi square vs fisher exact test
I'm trying to understand the reasoning by choosing a specific test approach when dealing with a simple A/B test - (i.e. two variations/groups with a binary respone (converted or not). As an example I will be using the data below
Version Visits …
L Xandor
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14
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How to compute the probability associated with absurdly large Z-scores?
Software packages for network motif detection can return enormously high Z-scores (the highest I've seen is 600,000+, but Z-scores of more than 100 are quite common). I plan to show that these Z-scores are bogus.
Huge Z-scores correspond to…
Douglas S. Stones
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What is the difference between Z-scores and p-values?
In network motif algorithms, it seems quite common to return both a p-value and a Z-score for a statistic: "Input network contains X copies of subgraph G". A subgraph is deemed a motif if it satisfies
p-value < A,
Z-score > B and
X > C,
for some…
Douglas S. Stones
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10
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Why does Stouffer's method work?
It seems like a fairly straightforward question, but when I really think about it, Stouffer's method doesn't make sense to me. This is why:
Assume a two-tailed hypothesis. You first calculate $z_i$ from $p$-values. So let's take a fairly simple…
will
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How can I find a Z score from a p-value?
How can I find a Z score from a p-value? I know how to look up the p-value from a Z score using a Normal distribution table, but I don't know how to calculate it.
For example, a question says the alpha equals 5 percent. From this, I see in my…
Juya
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Is there a way to define a statistic similar to the z-score for the Poisson distribution?
Let's say I want to compare samples taken from Poisson distributions that have different values of lambda (rate). If the samples were from a normal distribution, I could convert each observation into a z-score based on the mean and standard…
honi
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Why is $z$-value more meaningful than $p$-value for very low $p$-values?
In a comment to Jaap's answer to this question about reporting tiny p-values, amoeba says "Once the $p$-value is below 0.0001 or something ... it's probably more meaningful to look at $z$-value than at $p$-value," for example the 5$\sigma$…
R Greg Stacey
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Why would one ever use z-score over a t-score?
Forgive me if this seems like an elementary question, but no amount of googling has turned up a satisfying answer for me. From what I understand, a t-score should be used instead of a z-score when the sample size is considered small. I've also read…
user120800
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How can I obtain z-values instead of t-values in linear mixed-effect model (lmer vs glmer)?
I am wondering why in my lmer model the summary() only yields t-values rather than z-values, such as here:
model <- lmer(area~Register+(1|subject), data = ev)
summary(model)
Linear mixed model fit by REML
t-tests use Satterthwaite approximations…
Ping Tang
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What is Bartlett's theory?
This neuroimaging paper has been cited thousands of times. In it, a method is proposed for computing the correlations among several seed regions and all other brain voxels. Part of this method involves z-scoring Fisher z values:
To combine…
user28511
5
votes
2 answers
Z-score in the analysis of data
I am being provided z-scores of dependent and independent variables. I was checking if it can analyzed as such as raw data?
Alph
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Terminology - Comparing Z Scores
Let's say I have some sample of people with a measure of interest for each one, let's call it v. Let's say I measure v twice for the same set of people, one in January and one in December. Now I want to assess whether a person's v value improved…
user164846
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How to convert percentile rank into z score in R
I have a vector of percentile ranks. I want to convert them into z-scores, so it will be interval scale. I have to do it in R, but I could not find a function or package that can do this. Does anyone have any idea?
user2547924
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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:
pval = 2*(1 - scipy.stats.norm.cdf(abs(z)))
Where sf is survival function and cdf is Cumulative…
rnso
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