p value

  1. S

    p-value and estimation of parameters with non linear least squares

    Hi I am performing an estimation of some parameters . I Have the next data: I am using nls.lm() function, and I am trying to fit this data to a logistic distribution. In order to realize this I have defined the next things in R. edad<-datos$Age u_x<-datos$mx...
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    McNemars Chi squared Test Results

    Hi All, Hope this is the right place. I am QC ing some work of my senior and I am getting some drastically different P values for McNemar's tests. I'm using stata. Here is an example: Base Week 4 0 0 0 1 1 0 3 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 1 1 2 0 0 3 0 3 1 2 1 2...
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    How do I prove my results are statistically significant or not?

    Sorry in advance, I'm a complete statistics novice! I have a three chemical samples which were prepared in exactly the same way, and when tested have given different results. How would I statistically compare these? I was told by somebody to divide the average by the standard deviation to get...
  4. S

    MANOVA, when independent variable is not multi-level and P value significance varies!

    My research has 4 independent variables and 4 dependent variables. My hypotheses are constructed in such a way that 1 independent variable's effect size is checked on 4 dependent variables. My independent variables are not continuous but they are measured on a 7 item likert scale. And my...
  5. K

    Scatterplot relationship issue.

    Hi, the data below is just a sample of the data I am trying to enter into a scatterplot. The issue is that a previous correlation test shows a p value of 0.011, a clear relationship. However, when I took the averages of 196 entries of the data below, the scatterplot shows little...
  6. B

    model comparison, log likelihood score, P value.

    I am working on Bioinformatic analysis of genomic data. I am doing some statistical analysis and doing model comparison and have some conceptual doubts. And quite possible that it is a simple concept which I do not know, as I am not so through in statistics. I am comparing two models. One is...
  7. A

    Test Statistic and P-value Calculation???

    A 1995 survey indicated that 7% of the adolescents in this age group had tried marijuana. Assuming 7% was the true value in 1995, you want to perform a test to determine whether the proportion of kids in this age group that have tried marijuana has changed since 1995. Let α = 0.1. What is the...
  8. N

    Mann Whitney U - P Value of 0.0000

    Good Afternoon all, I am using a Mann Whitney U to compare two populations the data ranges from (-2 to 2). I have already done this on 4 different variables however for one of them I have repeatedly got a p=value of 0.0000 (Using mini-tab). C2 461 2.0000 C1 503 1.0000 Point...
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    Why does a larger sample size produce a smaller p-value?

    Hi, I need help with this problem... The obtained p value for a correlation analysis is .036, for a sample size is 50. If the analysis had been undertaken with n = 90, and the same sample correlation value was again observed, what would be the relative size of the p value for the second...
  10. A

    Multivariate Normality accepted at 5% significance level but rejected at 1% ??

    Hi, I am new to this forum. I am trying to test whether a set of variables in the data follow multivariate normal distribution. I found Mardia's test for this and below is the summary of the results : Mardia Skewness 58.29 <.0001 Mardia Kurtosis 2.43 0.0149 Henze-Zirkler T 7.52 <.0001...
  11. K

    crazy p-value

    I am taking data analysis, and am having a bit of trouble. It has been a couple years since i took intro to stats, so i am very rusty. I performed a t-test (two sided, and both alternates) on Sleuth 2 ex0222, and I get a p value with an negative exponent. this seems ridiculous to me, and I...
  12. M

    Dice's similarity coefficient (aka nei and li). significance...

    I've been struggling with the Dice coefficient for days now. I understand that the closer to 1 the cases are the more similar they are but is there some way of obtaining a p value for this to show some level of how significant this similarity is to one another? i can't seem to find anything...
  13. B

    Need help (ANOVA & ANCOVA)

    I'm writing my dissertation and I used ANOVA and ANCOVA. After a lot of trouble, I'm finally writing the results. But I don't know how to put the values. Someone told me I should write "(ANOVA; F(x,y)= Fvalue, p= pvalue)". But what should I write instead of x and y? I thought x was degrees of...
  14. S

    p-value and significance level

    In 1 sample t-test, where null: mean of sample is zero, I would think a high p-value like 0.30 would imply that null can't be rejected at 5% significance level. However, p-value of 0.012 would imply null will be rejected at 5% significance level but not at 1% significance level. So, I am...
  15. S

    One-tailed p values in repeated ANOVA?

    Hello, I am examining the results of 3 groups on a series of tasks using repeated ANOVAs (mixed model), which include 2 within subject factors. I hypothesise that my two clinical groups will perform worse than the control group on all the task, but I don't have priori hypotheses regarding the...
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    how to exclude block effect (I think)

    Hi, I have done a simple experiment, with one control group and one treated group. Each group have between 3-5 replicates. The whole experiment is repeated three times. If i do a normal student t.test for each experiment i get a significant difference, however if I do a student t.test...
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    Spearman's Rank Correlation P value on Minitab

    Hi there, im doing a project on the relationship between plant height and their nearest neighbour. As i couldn't normalise the data i've opted to use Spearman's instead of Pearson's. Im using a large dataset and do appear to be finding a relationship, unfortunatly though im getting p values of 0...
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    chi square test

    I am running a chi square test, followed by a marascuilo test to compare a binary resonse with categorical variables as the independent variables. The dilema is that my total sample size is 1,000,000 so I am getting chi square values in the thousands, with no major differences in the actual...
  19. N

    Correlation test more than 30 samples

    Hi, I have some questions about correlation please. I have 129 samples, each of which has two variables, distance from sea and amount of sample colonised. I have determined the data is not normally distributed, so thought a Spearman's Rank test would be appropriate to test for correlation. I...