# Tagged Questions

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### How to determine if % selecting Option A is statistically different from selecting Option B in a survey?

I ran a survey on pricing and asked respondents to choose between option A or Option B. 61% chose option A and 39% chose Option B. The sample size is 90. How do I determine if the % selection Option A ...
32 views

### Significance of time course difference over interval

I am dealing with some data which plotted looks like: I would like to add a level of significance to my claim that the values of the two time courses are different over the latter half of the ...
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### When n increases the t-value increases in a hypothesis test, but the t-table is just the opposite. Why?

The formula for $t$ in a hypothesis test is given by: $$t=\frac{\bar{X}-\mu}{\hat \sigma/\sqrt{n}}.$$ When $n$ increases, the $t$-value increases according to the above formula. But why does ...
29 views

### Determining best approximator based on repeated measurements

I have a set of data (which I have attached a plot of for your convenience) in which I have 2 categories of interest - let's call them A and B. For each of them I want to select from a series of ...
106 views

### Comparing means with unequal variance and very different sample sizes

I am trying to compare the means of the same variable between men and women. This is the statistics: ...
96 views

### What is the most appropriate test for a multi-year different group/yr experiment?

I've been working on a research project for close to five years now. For my thesis I have to show how "well" did my approach improve things. Setup: Every year we use a tool A to brainstorm and ...
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### Relationship between test stat and p-value in relation to t-test

I was wondering why it is necessarily true that if a test statistic exceeds the critical value of t, then it will also be true that the p-value will not exceed the level of signi ficance.
284 views

### How to compare two groups with multiple measurements for each individual with R?

I have a problem like the following: 1) There are six measurements for each individual with large within-subject variance 2) There are two groups (Treatment and Control) 3) Each group consists of ...
125 views

### R-squared vs. t-test confusion

I am using regression tree for this educational exercise. I have 500 observation points of independent variables $X$ and dependent variable $Y$. I use 400 points to generate my model and keep 100 ...
47 views

### Comparing general search engine and a meta search engine. Paired t test or independent t-test?

I have built a domain-specific search engine, a meta-search engine. This search engine, of course, take its results from other search engines like Google, Bing, Yahoo and stuff. Then does some ...
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### ANOVA with 3 groups- does adding a group close to the mean reduce power?

Sorry for that horrible title. I have run a psychology experiment where participants received one of three sets of instructions (between-subjects). Either they were told to approach the experiment a ...
109 views

### t-test, chi-squared test or Poisson test?

I have to compare the survival proportion between two treatments. Because of some limitations, I can only take a sample of $n_{1}=5$ animals from treatment 1, and $n_{2}=50$ animals from treatment 2. ...
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### Paired-sample t test for usability scores

I have conducted an empirical study as a part of my master thesis. Each test subject filled out a questionnaire where some questions were regarding usability of different features. What is the ...
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### Which statistical test to use? Paired-sample or independent-sample?

I have 1 subject rating 40 participants on the big five personality traits and other variables. these 40 participants are in 2 conditions (20 each). I want to compare whether there is a difference ...
324 views

### How to compute the t-ratio at 0.05 significance level?

My statistics program plots vertical lines representing a t-ratio at 5% significance level along with its sorted parameter estimates when fitting a linear model. I don't understand how this line is ...
142 views

### The result of absolute change and relative change in t test is different

My task is to evaluate the effectiveness of an intervention. In my study, there are one control group and one intervention group. There are two time points, baseline and endpoint. And I use the score ...
423 views

### How can you implement a two-way ANOVA with nesting in R or SPSS?

I currently am conducting a study where I have three variables: one that is binary, and two numerical ratio variables. Each of the subjects in my study has values for each of the three variables. ...
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### Which test to use for comparing changes in computer source code?

I am not sure which test I have to use to analyze my data. The situation is as follows: I have two computer programs which are doing exactly the same. Both share a large amount of source code, but ...
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### Appropriate test for difference in trials with varying calibration

Let's say I collect data from an experiment where for each measurement device, 5 trials are conducted at different temperatures. Each device is calibrated separately, and the 5 trial temperatures are ...
210 views

### Significant Statistical difference One-sample t-test

I am trying to test if one algorithm is statistically significantly faster than another using the One-sample t-test These are the results I have and I am trying to prove Algo2 is significantly faster ...
2k views

### Comparing two classifier accuracy results for statistical significance with t-test

I want to compare the accuracy of two classifiers for statistical significance. Both classifiers are run on the same data set. This leads me to believe I should be using a one sample t-test from what ...
459 views

### Tracking down the assumptions made by SciPy's ttest_ind() function

I'm trying to write my own Python code to compute t-statistics and p-values for one and two tailed independent t tests. I can use the normal approximation, but for the moment I am trying to just use ...
395 views

### Comparing smoke and hormones level in two groups of people. Which test?

I'm totally not a pro in statistics so i hope the question is not too simple! I have two groups of patients. One group are smokers, the second are non-smokers. I want to compare the level of some ...