Tagged Questions

0
votes
1answer
19 views

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 ...
3
votes
1answer
103 views

What statistical test do I need to see if there is a correlation between two different instruments?

I want to do a study to examine if there is a correlation between nursing students' confidence & satisfaction, and their intuitiveness. I have two instruments, The Student Satisfaction and ...
0
votes
1answer
48 views

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 ...
3
votes
3answers
149 views

Does low significance prove my hypothesis wrong?

Thank you for taking time for reading and attempting to answer my question. I have no idea about statistical testing yet I am doing a research project on a sample size of 40; it is a correlational ...
2
votes
0answers
109 views

Statistical significance of increase in correlation

I have a sample with some individuals, and also three variables measured for each individual, let's say $A$, $B$ and $C$. There is a mild correlation between $A$ and $B$ and a mild correlation ...
2
votes
0answers
25 views

Estimating the likelihood of independence of two discrete variables using the co-occurrence count matrix

I have some data about users from different regions visiting different directories of some website. Aggregating that data I get the co-occurrence frequency matrix (for regions and directories). Now I ...
1
vote
0answers
27 views

Test to use to measure the association of half-deciles

I'm querying a large (100 million row + ) SQL Server database and doing some preliminary work on the correlation between visits to the emergency room and total healthcare costs. I ran a query and the ...
4
votes
3answers
215 views

Big Data vs multiple hypothesis testing?

Nate Silver in his excellent "The Noise and the Signal" warned that we are much in awe of Big Data. But, that Big Data predictions in many fields have been disastrous (financial markets and economics ...
2
votes
0answers
92 views

test for correlation of a multivariate non-normal distribution

Assume I want to generate a sample of n-dimensional vector $z$ with a given correlation matrix $Corr(z)=R$. Some of the margins of its distribution are not normal (if you're interested here's the ...
1
vote
1answer
138 views

How to test for serial correlation of a time series itself (not residuals)?

We know that Ljung-Box test can be used to test for the residuals of a fitted model. But to test for the serial correlation of a time series itself, is there a way to do that?
2
votes
1answer
364 views

Compute significance of Kendall tau-b?

Compute significance of Kendall tau-b? I have so-far tried all ways of computing kendall tau significance (where there are ties) described here. However, none of them works good, even for relatively ...
0
votes
1answer
50 views

Questions regarding correlation

I'm writing a thesis about cooperating competition between companies. I have a few problems with the last two research questions: RQ7: Are there any differences between the perception of costs and ...
1
vote
0answers
20 views

Different representations of the one-tailed/one-side hypothesis test [duplicate]

Possible Duplicate: What hypothesis for A is better than B? Consider the Pearson correlation estimate $r$. I want to do a hypothesis test. $$\text{Option 1}$$ $H_0: \text{corr}(X,Y) \leq ...
0
votes
0answers
130 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 ...
0
votes
1answer
662 views

Measuring correlation or dependence between two data sets

Is there any statistical test or measure to evaluation the degree of correlation or dependence between two sets of data-points ?
0
votes
2answers
194 views

How to test for a monotonic relationship between two variables, without assuming a specific functional model?

I'd like to test the hypothesis that there is a monotonic relationship between two variables, without assuming a specific model. What is the most robust (i.e. lowest probability of type-II error) way ...
1
vote
1answer
328 views

Significant regression coefficients but non-significant bivariate correlations [duplicate]

Possible Duplicate: How can adding a 2nd IV make the 1st IV significant? For two of my main variables, the bivariate correlation coefficients (with the outcome measure) are non-significant ...
0
votes
1answer
44 views

How do you choose the timeframe for a prediction to be tested?

To (hopefully) clarify the question a bit more if you have a broad working hypothesis that x influences y, on a causal/predictive basis (e.g. if x goes up in time t, then you would expect y to go up ...
2
votes
3answers
636 views

Correlation coefficient contradicts t-test

I am looking at the probability of opting into a program based on a continuous variables $X_1$, $X_2$, $X_3$, etc. When I divide the sample into people who opted in and did not opt in and do a t-test ...
5
votes
2answers
537 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?
2
votes
0answers
48 views

Analysing choices pattern

we have a process in which, at each step, a set of elements are presented to user, the user choses one, his choice is recorded and next round starts with a new set of elements. For example: 1. ...
1
vote
1answer
467 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 ...
1
vote
3answers
108 views

Are observations consistent with each other?

I have 60 apps. For each app, I look at 10 review of that app, and count how many of the reviews say the app is unreliable. Let $X_i$ denote the number of such reviews, for the $i$th app. I want to ...
3
votes
1answer
312 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 ...
1
vote
1answer
220 views

Multivariate correlation in sensitivity analysis

I have a vector of parameters $\theta=(n,ph,pt,\gamma)$ which are fed into a process which produces a result. I would like to quantitatively report the sensitivity of the result to the variation of a ...
4
votes
3answers
358 views

Akaike Information Criterion and composite variables

Akaike information criterion is a measure for goodness of fit of a model that compensates for the number of parameters that were used to build that model. Consider two linear models, one that is ...
12
votes
5answers
4k views

Example of strong correlation coefficient with a high p value

I was wondering, is it possible to have a very strong correlation coefficient (say .9 or higher), with a high p value (say .25 or higher)? Here's an example of a low correlation coefficient, with a ...
2
votes
1answer
103 views

Chi square based measure for fairness?

I have some project categories $(PC_1, ... ,PC_n)$ and some institutions $(I_1, ..., I_n)$ and would like to determine how fairly projects are assigned to institutions and their project categories by ...
8
votes
1answer
2k views

Can we compare correlations between groups by comparing regression slopes?

In this question they ask how to compare Pearson r for two independent groups (such as males vs females). Reply and comments suggested two ways: Use Fisher's well-known formula using ...
4
votes
1answer
1k views

How do I compare correlation coefficients of the same variables across different groups?

I am testing the correlation between Variable A and Variable B by gender and marital status. So I have the coefficients for males and females and single, married and other. I want to compare the ...
9
votes
4answers
850 views

Changing null hypothesis in linear regression

I have some data that is highly correlated. If I run a linear regression I get a regression line with a slope close to one (= 0.93). What I'd like to do is test if this slope is significantly ...
7
votes
4answers
584 views

What test to compare community composition?

Hope this newbie question is the right question for this site: Suppose I would like to compare the composition of ecological communities at two sites A, B. I know all three sites have dogs, cats, ...
2
votes
2answers
531 views

Hypothesis test for whether correlation coefficient is greater than specified value?

I want to test whether a correlation coefficient is greater than 0.5. What should the null and alternative hypothesis be? Should I do a two tailed test or one tailed test? Thanks
4
votes
1answer
91 views

Construct probability that measurement belongs to one of two sets

We are dealing with a measurement apparatus that is cursed by noise and are trying to find out if a measurement was noise or an actual measurement. Assume we have a beam of light incident on an ...
5
votes
2answers
2k views

How to estimate a critical value of Spearman's correlation for n=100?

I have searched a lot, and I can only find tables that show critical values up to n=30. Can someone provide, or point me to, a simple method of estimating this value for different $\alpha$?
0
votes
2answers
933 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 ...