significance

  1. H

    Correlation matrix with significance

    Does anyone have a ready-made function or know a way to produce a correlation matrix with asterisks marking significance levels in R?
  2. N

    significance of the difference between two values

    Hello all, I'm working on a skew-normal distribution and would like to know if the difference between 2 values of the data set is significant. It's the distribution of Mutual Information between couples of lemmas (100,000 of them). You can see the distribution on the jpg image. What I...
  3. C

    Author's interpretation of Odds Ratio and Confidence intervals

    Hi all, Having some difficulty understanding the results of this paper I am including in a review. It compares the effects of 3 interventions aimed at preventing HIV on couple's relationships. A multivariate logistic regression is used and effect estimates are given (which we are told are odds...
  4. D

    Simspons Diversity Index

    I have calculated the simpsons diveristy index for three different strata: Understorey (1-D= 0.55), Subcanopy (1-D=0.77), canopy (1-D=0.83) How can I test if there is a significant difference between these? Do I need to? Any help would be greatly appreciated. I have had a play around in...
  5. W

    Time Series - Difference over time

    Hello, I'm new in the time series, so I need some help. I have a short time series (5 quarters), with the proportion of a parameter (public transport-user people). I know there are some effects of TS (trend, seasonal, cyclic and random). I would like to testing the (significant) difference...
  6. K

    Correlation betweeen k binomial variables

    Hello, This is my first post as a new member, so hope I'm posting this in the right place... I need a general formula to calculate the minimum sample size N required to determine whether k binomial variables are somehow correlated (either positively or negatively) at significance level p<=...
  7. J

    How do I test the significance of my correlation coefficients for various regressions

    Hi, I have a set of 25 points and I used a TI-84 calculator to calculate the linear, quadratic, logistic, exponential, and power regression models for this data set. I have, likewise, obtained the r^2 value for each of these regressions. Some of these r^2 values appear to be quite similar. For...
  8. W

    Is it meaningful to calculate a p-value based on a convenience sample?

    Ignore the bootstrap as a possibility. If the answer is no, then what is the point of stating the p-value (especially if it is, say, 0.10)?
  9. X

    Minimum control size for determining effectiveness of treatment

    So the following scenario I have a treatment that I know to be effective, but I want to determine precisely how effective it in a (large) group of individuals I'm dividing them in to a test group and a control group so I can compare the effect of the treatment However, I want to keep the...
  10. C

    Statistical Design of Experiments: Impact of missing and/or changing experiments

    Hello, I am new to both this forum and the concept of statistical design so please, treat me like the novice I am! OK, so I am hoping to carry out experimentation on a material. I am testing five different physical parameters of 4 different materials, all of the factors are numerical (i.e...
  11. L

    Can you help me decide if there is statistical significance here?

    Hi, I've attached a word file - it contains exam results. There were two sessions - one AM and one PM. . I am trying to work out if there is a statistical significance between the achievement of the AM and PM groups and whether moderation should have occurred here? Can anyone help? I have...
  12. D

    Finding Significant Difference between Linear Regressions

    Hello. I have a scatterplot with two different sets of data plotted. Each individual set has its own linear regression formula and R-squared value. What type of test could I run on Microsoft Excel to get a p value to see if one dataset's trend is significantly different than that of the other...
  13. K

    Statistical test for comparing means of correlation coefficients

    Suppose that I have two lists of correlation coefficients such as A = [0.5,0.3,0.25,0.3,-0.1] and B = [0.8,0.7,0.75,0.8,0.8]. The correlation coefficients in A are independent to B. Now, I want to test the null hypothesis, that the means of both lists are equal. I am familiar with how to...
  14. K

    Interpreting pairwise comparisons for significance when you have 3 groups

    Dear posters, I am currently trying to interpret results from three different groups in my study. There is essentially a control group and two picture groups. My original hypothesis would be that one of the picture groups would outperform the other, but post hoc testing revealed something...
  15. E

    Error bars don't overlap but aren't significantly diff. - interpretations/reasons?

    Hello all, I'm struggling to understand/interpret my graph and kruskal wallis test. Basically, I've created a bar graph which looks pretty good. There are 5 bars, each with error bars, and none of the error bars overlap. All of my 5 groups look significantly different. HOWEVER, when I do a...
  16. W

    Statistical Difference vs. Norm

    Hello, I would appreciate your help with something. I have a study to test an advertisement of n=150. The results are given as percentages for each answer. I also have a norm composed of the average of 18 previous studies, all n=150, with identical questions giving me a sample size of...
  17. S

    SigmaPlot: Statistical Significance

    Hey guys, I'm trying to add statistical significance data to a graph I have already generated on SigmaPlot (vertical bar with error bars). I have already generated the p values which determine the significance, but cannot find a way to add them to the graph. I was thinking adding data labels...
  18. rogojel

    bonferroni correction in multivariate regression

    hi, I just read something that made me think about this, the p-values we calculate in a multiple regression have no adjustment for multiple test ( like a Bonferroni correction), right? Does this mean tjat more independent variables I have the more probable it is that I get false positives ...
  19. P

    Testing whether two related slopes/intercepts are different from each other

    Hi, I'm new and stuck. I want to see if the intercepts and slopes of two linear regression lines are significantly different. I thought I found the solution but now it looks like that might not work because the data is overlapping. Specifically: I have data for X, Y1, and Y2. I can find the...
  20. M

    Which test? - Significance of Sample Size

    Hi all, (First-time poster) I'm working with tagging data for 35 tracked fish. Each fish was tracked of 3 seasons, with detections (3873 overall) corresponding to a fish entering the detection area of one of the many placed monitors within the study area. I would like to perform a stats...