In hypothesis testing, the $p$-value refers to the probability of seeing a result as extreme (or more so) than the one observed, given that the null hypothesis is true. When the $p$-value is small, then there is good evidence that the null hypothesis is false, since it would make the observed data ...

learn more… | top users | synonyms (2)

2
votes
1answer
27 views

Is positive coefficient of price correct in a multiple regression model

I am currently undertaking forecasting of energy sales (kWh) for our industrial customers. From historical data gathered from 1993 to 2013, a graph of price per kwh against sales kwh shows a positive ...
1
vote
0answers
22 views

Best proportions test based on counts (accuracy, distribution, etc)

I'm trying to compare two sets of counts over totals. For example, subject 1A will have 40 out of 600, and subject 1B will have 3 out of 20. How do I compare these proportions and counts while taking ...
0
votes
0answers
22 views

Iterative Addition of Variables to Model Based on P Value

Suppose I have 64 columns that I have chosen out of 500+ columns based on the fact that they have the highest pairwise correlation (is this a good way?). I take 16 of these columns and run a simple ...
0
votes
0answers
18 views

Am I using Fisher method correctly?

Suppose I want to test the hypothesis that speed of light is always below $c$ (note: regardless of the medium). [Also, this is just a fake example, so pretend we don't know any physics theory] Now, I ...
0
votes
0answers
14 views

P-values equal to 0 in permutation test

I have two datasets and I would like to know if they are significantly different or not (this comes from "Two groups are significantly different? Test to use"). I decided to use a permutation test, ...
0
votes
2answers
24 views

Overall Significance vs. Individual Variable Significance in Mutliple Regression

I'm running a statistical analysis for work in which I'm trying to determine which (if any) key economic indicators influence our sales. Here is the summary data that I'm getting when I run a ...
0
votes
1answer
39 views

What are the null and alternate hypotheses? Will you use a left, right, or two-tailed test?

Ben has a coin which he claims is weighted in a way so that when he flips it, heads appears more often than 50% of the time. He tries to prove it to you by flipping the coin 100 times, which ...
0
votes
0answers
29 views

Significance of varibles after stepwise regression

I did stepwise regression with my multiple regression model and using AIC as a measure of fit with the step function in R. Afterwards some variables that the ...
0
votes
0answers
17 views

This minitab blog suggests that very large sample sizes can be bad, what's going on? [closed]

I often have sample sizes of over 10k so this is a bit worrying to me. Here is the blog page with several examples where small sample sizes appear to trump large sample sizes. ...
3
votes
0answers
43 views

SPSS: Pearson's r not significant but confidence intervals do not include 0

I have calculated the value of Pearson's r between two variables in SPSS, two tailed. Sample size is 81. The r value is -.02. The p value is .06. When I compute the 95% confidence intervals using ...
5
votes
2answers
244 views

Interpreting one- and two-tailed tests

How do you report results that give you a p-value of 0.08 for a two-tailed test and a p-value of 0.04 for a one-tailed test? Generalizing the issue, if you obtain a p-value between 0.05 and 0.9999 ...
1
vote
0answers
61 views

F-statistic value is too high for my model

Number of obs = 501 , Method: Fixed-effects regression Number of groups = 101 F( 10, 100) = 3422.31 , Prob > F = 0.0000 , ...
0
votes
0answers
20 views
0
votes
0answers
41 views

Quantifying Potential for Violence/Espionage

I am planning a seven-question Likert-type survey with a "1 to 10" scale. The questions I am asking in the survey are to assess an individual's risk factors (how much risk they present to an ...
3
votes
0answers
30 views

two-sample Kolmogorov-Smirnov test in R p-value confusion

I'm confused about the appropriate interpretation of p-values returned by the two-sample Kolmogorov-Smirnov test (ks.test) in R. In slide 23 of this presentation about non-parametric two-sample ...
4
votes
3answers
59 views

Understanding $\chi^{2}$ and Cramér's $V$ results

I have two groups of buyers, A and B, and I want to test whether the difference between the percentage of them who would buy a ...
3
votes
2answers
191 views

Is p-value also the false discovery rate?

In http://surveyanalysis.org/wiki/Multiple_Comparisons_(Post_Hoc_Testing) It states "For example, if we have a p-value of 0.05 and we conclude it is significant the probability of a false discovery ...
0
votes
1answer
26 views

interpretation of little's mcar test

My little's MCAR test revealed chi-square = 27.120, DF = 1974, and sig. = 1.000. 74 items and 151 cases. So, can I concluded that the data were missing completely at random since the p-value is not ...
4
votes
6answers
125 views

How to explain borderline p-values to non-stats people

I ran an OLS regression, and the p-value of one variable is 0.065, which is more than the threshold to consider statistically significant. However, it's not too bad either, as my data has only 300+ ...
0
votes
2answers
21 views

What are correlations among between test statistics in multiple comparison procedures

In the book Multiple Comparisons Using R Bretz et al write that their R package multcomp improves power above other multiple comparison procedures by "accounting for the structural correlations ...
3
votes
1answer
125 views

Calculate a 95% confidence interval and p-value for the change in C-statistic using bootstrap with R

I am using boot() and boot.ci() to furnish confidence intervals for the difference in the $c$-statistic (AUC) between models ...
4
votes
4answers
286 views

What is the meaning of a large p-value?

I understand that the $p$-value is the conditional probability of observing the test statistic or something more extreme given that the null hypothesis is true. I have read the great explanation by ...
0
votes
0answers
31 views

Interpretation and understanding results from a chi square test for independence

I'm making a chi square test on data that has information about students. I want to find out whether there is a relationship between how well the students did on a particular test and the level of ...
2
votes
0answers
33 views

Chi-squared test and binomial distribution

In some circumstances the Chi-square test can be replaced by a test based on the binomial distribution. The common issue with using the binomial distribution is that it may quickly become tricky to ...
0
votes
1answer
32 views

Why does bootstrap gives different p-values for CC and my regression coefficient in simple linear regression?

I'm using R and the package boot. my boot function returns the coefficients and the r.square and sqrt of the r.square ...
0
votes
0answers
182 views

For what p-values can you say the data approached significance?

I am in the field of clinical psychology, where statistical significance is commonly said compared to p = .05. For what values of p can I say data APPROACHED significance?
1
vote
0answers
14 views

Fisher Exact Test Correlation Value [closed]

I have run the Fisher Exact test for several larger than 2x2 matrices. I got a Value number and a P value instead of just a P value. Does this mean the test ran out of memory and is invalid? or...Why ...
1
vote
1answer
111 views

Regression coefficients with longitudinal data yields different results in R and SAS

I have a question about SAS and R. For a research, I used a longitudinal data and I initially used SAS (GLIMMIX) and then I analyzed the data with R (...
2
votes
1answer
48 views

Hypothesis testing for multiple choice quiz

I am trying to determine whether students perform better than chance on a quiz with $q$ multiple choice questions. Each question as 4 possible responses; one is correct and 3 are wrong. A correct ...
2
votes
0answers
66 views

“How-to”: omit p-value and use N-P approach in practice?

I've been reading a variety of articles 'bout p-value controversy and since the best way to understand theory is to practise it, I devised an example. Suppose, I'm a psychologist and I conducted an ...
0
votes
0answers
16 views

Integrating p-values (or z-scores) with missing values

I would like to apply a Stouffer (or Fisher) integration on a list of p-values or z-scores. However, some of them contain missing values. E.g. (R snippet): ...
0
votes
1answer
47 views

Calculate p-value for main effect in 2x2 design

How can I obtain a p-value for a main effect in a 2x2 design? I have 12 participants and 2 independent condition categories which I represent by letter, and case. That means my conditions are A, a, ...
0
votes
1answer
76 views

High p-values for logistic regression variable that perfectly separates?

I'm using R to run some logistic regression. My variables were continuous, but I used cut to bucket the data. Some particular buckets for these variables always result in dependent variable being ...
1
vote
1answer
135 views

How was this p-value calculated?

Sorry to ask such a blunt question, but I'm running out of time and I just can't figure this seemingly simple thing out. It's the p-value for $B_0$, a single variable regression. $H_0: B_0=0$ and ...
1
vote
1answer
37 views

Which method of df for chi square I have to apply either $(c-1)\cdot (r-1)$ or df$=n-1$? [closed]

I have 10 question, based on 5 Likert scale choices. How do I find degree of freedom here in Chi square? Some one says use $(r-1)\cdot (c-1)$ but I think it will apply on categorical data, my data ...
1
vote
2answers
64 views

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 ...
0
votes
1answer
38 views

How to compare two classifications' classes' size?

I want to know if, between two classifications, one provides more homogeneous classes size than the other. I devised to use the chi square test (classes' size are far more than the rule of thumb of 5 ...
0
votes
0answers
10 views

Comparing p-values from multiple permutation (Mantel) tests on variations of the same data set

I am comparing the relationship between genetic and geographic distance of individuals in a wild animal population. The hypothesis is that individuals with higher genetic relatedness establish home ...
0
votes
0answers
28 views

Comparing 2 sets of observations

I am analysing signals from 5 sensors and comparing what they pick up between day and night. Each sensor records a time series and this is compared to a reference time series to determine whether what ...
1
vote
1answer
38 views

How to test if time series are not cointegrated?

Is there a test whose null hypothesis is that time series are cointegrated? There are lots of tests whose null is no cointegration. How can I calculate a p-value for the null that two series are ...
0
votes
1answer
23 views

How to summarize multiple adjusted pvalue into a single measure?

Suppose I have a test with multiple hypotheses. For example, if I have X as a gene set (a set of symbols), and A, B, C pathways (sets of symbols), I am testing if A is enriched in X, B in X, C in X ...
0
votes
0answers
58 views

Interpreting Granger causality test's results – i.e. $X = f(Y)$

The following is generated using http://www.wessa.net/rwasp_grangercausality.wasp: ...
2
votes
0answers
39 views

Comparing 6 week mean to current weeks actual

I am trying to catch changes in customers sales from week to week using R. ...
0
votes
1answer
58 views

In Fisher Exact test, why the more data you have, the more pvalue drops to smaller values?

Suppose I have a contigency table 18 2 3 40 If I collect more data, it is likely that I obtain a matrix like this ...
0
votes
0answers
30 views

Assessing clustering statistical significance

I read a good tutorial on the p-value. Everything there is clear for me, except how I can define the null hypothesis. I found an example (on page 6) in this paper using p-value to judge the ...
1
vote
0answers
35 views

Exact p-values for real world outcomes

I had an interesting exam question yesterday, in which you had the outcomes of number people killed in traffic accidents in two subsequent years (the second being relatively higher than the first). ...
0
votes
2answers
93 views

Significance of Regression Intercept (R lm model) [duplicate]

Question: Having performanced a linear regression in R with the lm function, I'm not sure how to interpret the results for the Intercept (as shown below). It seems the probability of the ...
0
votes
1answer
84 views

How do I test statistical significance between normally distributed data and non normally distributed data?

I have observed values (80 in total) in different measured circumstances (80 in total). I want to test whether my observed values are the result of chance or do measured values affect my observed ...
0
votes
1answer
111 views

Where does p-value come from in McNemar's Test?

I was using this online calculator to work out McNemar's Test on this data set: I get the results: The two-tailed P value equals 0.1859 Chi squared equals 1.750 with 1 degrees of freedom. ...
1
vote
1answer
36 views

Intepreting p-value of a regression coefficient

I was wondering how you interpret the p-value of a coefficient for a multivariate linear regression. Is the p-value intepreted only when everything else is fixed? Is there a way to incorporate the ...