# Tagged Questions

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### What statistical test is appropriate for correlations within repeated measures?

We have $N$ individuals measured repeatedly in time. For each individual, at each measurement, we measure the values of two variables: $A$ and $B$. The number of measurements per individual might ...
74 views

### Correlation vs. independence: statistical power, available tests

Correlation is frequently applied, but in fact often the interest of the experimentalist is not so much to find a significant correlation as a significant dependence of the variables, and clearly ...
46 views

### What is the analysis techniques for comparing two sets of ratings

Say, I have collected 50 comments. For each comment, I am planning to get 10 ratings from non-expert raters for the following criteria: "interesting vs. not interesting". Based on the plurality of ...
111 views

### Help translating the following PCA results into layman's terms?

As a non-maths doctoral candidate, I would be absolutely thrilled to bits if anyone here might be willing to take a stab at translating the following PCA results into layman's terms. There are only ...
100 views

### Correlation not significant - interpretation?

Sorry that the question may sound stupid, but I'm really confused right now. For getting to know statistics better, I replicated an existing study (same questions) and did the survey (n=66). I ...
156 views

### Pairwise Correlations--Multiple Comparison Correction

I have a dataset with two sets of variables defining each sample. I am performing pairwise correlations between each variable in the first set with every variable in the second set. I essentially ...
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### Significance of correlation with only 11 datapoints

I am currently working on my thesis and calculating some simple correlation coefficients. I only have 11 datapoints available, but I would like to assess the statistial significance of my results. The ...
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### Significance test for PMCC

149 students each sat two tests. My null hypothesis is that the product-moment correlation coefficient is 1, because each test should be an accurate indicator of current attainment. The actual PMCC ...
59 views

### How to measure which program is faster than another in a statistically meaningful way?

I am trying to compare 2 computer programs, X and Y, for speed. I want to determine which one is faster. I could, for example, chronometer those programs 20 times, take the average and state that the ...
135 views

### Correlation not significant because there is not enough variance?

I have a question about correlations again. I have a dichotomous variable that I want to correlate with the another one (metric) by using the point-biserial correlation coefficient. I get a ...
154 views

### Pearson correlation is not significant although effect is .30 What could be the reason?

I have a correlation between two variables of 0.30, hence a medium effect. but it is not statistically significant and I want to report the reasons for that. looking at the test statistic I see that ...
291 views

### Interpretation of Spearman correlation for small sample

I am currently being confused by different opinions regarding the spearman correlation interpretation. Some says, $\rho<0.2$ can be ignored as small/weak relationship, some says $\rho<0.1$, for ...
189 views

### Test for significance of correlation matrix

If one wishes to test if the correlations in a correlation matrix are statistically significant as a whole group, one can perform a likelihood ratio test of the hypothesis that the correlation matrix ...
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### Statistics test for concentration of extract effecting germination

I am undertaking biology course work and am a little stuck. My experimental hypothesis is: There is a significant correlation between increasing tomato extract concentrations and reduced seed ...
204 views

### Test to show when diverging linear regression models are statistically different

What method will allow me to identify the values of the independent variable where two (or more) diverging linear regression models are statistically different? e.g. Take two simple linear ...
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### How to prove that test 1 produces more results than test 2?

If I have 2 tests applied on a set of data, both tests either produce a result ( assume = 1) or no result ( NA , assume = 0 ). Is there a way to prove that test 1 produce more results than test 2 with ...
106 views

### Spearman rank recommended n size

Is there a recommended n to test for Spearman's rank correlation? I have 2 lists of around 10,000 items. I read that Spearman's rank correlation is fine between 10-30 , can I use spearman to compare ...
175 views

### Measuring statistical significance using correlation of ranked (ordinal) data

I am trying to do hypothesis testing and am wondering if I am setting up this problem correctly: My hypothesis is that the reviews of the computer parts for a computer model 'M' on website A ...
181 views

### p-value for correlation/co-occurrence in sets of intervals

I'd like to have a probability measure for the co-occurrence of intervals in two datasets of intervals. ...
369 views

### Correlation of bivariate grouped data?

Which test should I use, if I want to test the correlation between 2 bivariate grouped variables? The case is: I have asked several hotel owners about their feelings about the occupational rate of ...
112 views

### Distribution of $R^2$ for pairs of random variables

if I have two uniform random variables $X$ and $Y$, and I sample $N$ values for each, what's the probability of getting an $r$ Pearson's correlation coefficient (or Spearman correlation) between them ...
490 views

### Assessing scale reliability: how to get the p-value for corrected item-total correlation?

I assessed the internal reliability of a self-created scale with eight items (N total = 150) by calculating Cronbachâ€™s Î±. It appears that one item correlates low with the overall score of the scale ...
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### Can I compare correlations even though one is NOT significant?

I have 2 groups and 2 correlation coefficients that I would like to compare using Fisher's transformation. Unfortunately, one of these coefficents is not significant, so not different from zero. Can ...
1k views

### How to explain significant correlation between independent and dependent variable but non significant regression test in the presence of mediation? [duplicate]

Possible Duplicate: Not-significant F but a significant coefficient in multiple linear regression In my research, I use Optimism as the IV, Job Satisfaction as the DV and Work-Family ...
889 views

### Increase sample size for significant correlation

At the moment I have $5$ paired samples for correlation. Spearman's R is $0.2$ and the $p = 0.78$. How do I calculate the number to extra samples I would need to get a more significant p-value?
471 views

### Is there an easy way to calculate significant difference between two largely overlapping correlations from same sample?

I am comparing three different measures comprised of 10-20 items each. Each of these measures is actually a short form of a longer 40-item measure and each of the short forms shares some similar ...
437 views

### How to quantify statistical insignificance?

I'm relatively new to statistics, and understand that my question may be completely misworded. I am testing my own algorithm versus another. While the outputs are not identical, I want to show that ...
524 views

### Calculating statistical significance between dependent Spearman coefficients

I have a set of scores on a specific dataset given by human evaluators, let's call it HJ. I also have the scores of two computer models on the same dataset, let's ...
2k views

### What statistics should I use to compare percentages?

I am trying to see if there is a statistical significant difference between the amount of bycatch in 5 different types of gear used by fishermen. For each gear I have varying number of replicates as ...
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### Tests significative with parametric calculations and non-significative with non-parametric ones! [duplicate]

Possible Duplicate: Comparing smoke and hormones level in two groups of people. Which test? I'm analyzing some data for an article about hormones concentrations and smoking. I was unsure ...
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### 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 ...
382 views

### P values seem to be the wrong way around

Say the null hypothesis is that two samples emanate from two distributions with either equal medians or equal variances. And p values are the probability that a value or more extreme comes from the ...
345 views

### How to compare two discrete series?

Suppose I have two series of numbers and they don't have to be time series. $S_1=$ {9,8,1 ...} $S_2=$ {7,9,2 ...} What are the methods to compare these two series and make a conclusion such that ...
115 views

### Correlation significancy measure for multiple predictions

I'm not sure what statistical test to use in the following situation: I have three different algorithms producing regressions for an observation. I now want to know, which of the algorithm yields ...
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### Significance and extending simple time series correlation

Using a very simple set of data I ran a simple correlation using Google spreadsheet. I got a -.83+ correlation, which is pretty strong. So now I am wondering what else I might be able to determine. ...
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### How to assess differential risk of disease across three groups after adjusting for other risk factors?

I have 3 different groups: A, B, and C: A (has a medical condition) has 30 entries B (another medical condition) has 31 entries C (control group) has 55 entries All participants have information ...
457 views

### Assessing significance of correlation

I have two variables, and I can calculate e.g. the Pearson correlation between them, but I would like to know something analogous to what a t-test would give me (i.e. some notion of how significant ...
1k views

### Analysing questionnaire data

I want to test if there is a rivalry among two siblings in a family. I have 15 questions in my study and I let my 100 respondents ( distributed equally to two siblings) ranked them 1 to 15. How ...
4k views

### Correcting p values for multiple tests where tests are correlated (genetics)

I have p values from a lot of tests and would like to know whether there is actually something significant after correcting for multiple testing. The complication: my tests are not independent. The ...