177 z-test questions.

methodology to analyze differences between groups

0 answers, 17 views proportion z-test
My dataset (n=2,000) shows total daily sales and I can plot a trend and show via a s-test that the average number sales is different in 2016 vs 2017. I also have the information in the data indicating ...

Comparing Means: Multiple Dependent Variables

1 answers, 914 views t-test manova z-test
I am using school-level data to compare mean scores for two groups (Group A schools and Group B schools), as measured by a series of indicators: 1) grade-level exam percentile, 2) percent of male ...

What hypothesis test should I use to compare the overall performance of two different athletes in a 100m race?

1 answers, 15 views t-test chi-squared z-test
I am sourcing data from IAAF's website to test my hypothesis - Athlete A is a better athlete than Athlete B (comparing their times in the Olympics). Since I would be sourcing the data from IAAF's ...

2 two samples, hypothesis test of proportions t or z test

1 answers, 727 views t-test proportion z-test
I have two samples of documents where one sample contains documents of a certain category and another sample contains documents of another category. I am analysing the occurrence of a certain word in ...

What would be appropriate test to compare two lists of dichotomous variables?

Colleagues, can't wrap my mind on simple question, please help! I have two products and list of their attributes. My respondents make an answer which product on each attribute they prefer. Finally ...

Should I be using Z-tests or T-Tests for my scientific data?

0 answers, 37 views hypothesis-testing t-test z-test
I've conducted a survey for my thesis where I ask a series of questions of the format:A statement relating to the experimentThen the participants answer ...

1 Comparing distribution of sample proportions to population proportion

I'm trying to find out whether there is a statistical method for comparing a distribution of sample proportions to a distribution of population proportions. For example if I have only two groups, A ...

5 z-test for one population proportion hypothesis with a small sample size

1 answers, 425 views t-test small-sample z-test exact-test
I have asked a "yes/no" question to a small group of people (n = 22). From the 22, 14 answered "yes" and 8 answered "no". I'd like to find out, with 90% confidence, if the majority of my population (> ...

Which statistical test should I use (comparing two cohorts)?

So I am doing some research in the field of Medical Physics, in particular radiation treatment with photons and protons. Now, I have two cases I am unsure about. 1) Here I have several patients. ...

algorithm for testing a variable

I want to test if a quantitative variable is different in 2 groups. As for what I understood so far, here is the algorithm I should use : if the length of my 2 subgroups are >30 --> z-test else, ...

How do I interpret a negative Z-test (two tailed for 2 proportions)?

I used my calculator to do a two tailed Z test for two proportions. Here's the data I input:X1 is 834 n1 is 3610 X2 is 145 n2 is 495I chose p1 not equal to ...

18 Choosing between $z$-test and $t$-test

Background: I'm giving a presentation to colleagues at work on hypothesis testing, and understand most of it fine but there's one aspect that I'm tying myself up in knots trying to understand as well ...

1 Z-test for One Population Proportion

I am completing a series of questions for this problem and I think I am following but one throws me off. The problem is a common one: In a study of smokers who tried to quit smoking with nicotine ...

1 Is there a non-parametric equivalent of the t-test for a small sample size?

2 answers, 262 views nonparametric z-test
I have weather stations collecting data (temperature, humidity, solar radiation, wind, etc.) inside and outside low-tech greenhouses. Four of the weather stations are inside, and one is outside. I am ...

3 What is the difference between Welch T Test and Z-test?

I have got 2 large samples and want to compare the difference. There are 2 methods: Assume the population variances are unknown and unequal, and use the Welch $t$ test. Assume the population ...

How to test statistical significance between percentages obtained at two intervals from single sample

I conducted a study on faculty improvement programs, whether they had an impact on teaching practices of faculty members. Sample size was 15. One of the categorical variable observed was 'Is the ...

1 One sample proportion test for weighted data

I have a sample of observations (n) representing individual evaluations (positive/negative) of pieces of text (n texts). Each individual can evaluate more texts (thus there are m individuals with m &...

McNemar or z-test?

I'm doing a matched sample evaluation to see if there is a statistical difference in graduation rates at a college for total sample and sub-groups within the sample after a policy change intended to ...

6 Why would one ever use z-score over a t-score?

1 answers, 1.607 views t-test z-test z-statistic
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 ...

1 SPSS Categorical Data: Residuals in Crosstabs

I would like to know what's the difference between the standardized residuals and the adjusted standardized residuals in cross-tabs cell display in SPSS? The following definitions are the ones that ...

Comparing 2 sample proportions from independent populations

1 answers, 56 views proportion z-test
Consider a hypothetical situation, due to a new teaching method being implemented, I want to test whether there is a significant difference in the proportion of students that have passed a particular ...