standard deviation

  1. hlsmith

    Bayesian Posterior: SD = SE?

    I was curious if the standard deviation in a Bayesian posterior is equal to the standard error?
  2. B

    It's posible to compare two means without considering standard deviations?

    My doubt is the following 'it's possible to compare means of two independent groups without considering standard deviations" ? For example: Control Group: mean +- standard deviation 50 +- 10 mm Experimental Group: mean +- standard deviation 100 +- 30 mm I am very...
  3. N

    Posterior of a Lognormal Shape Parameter, in Terms of Prior Location & Shape

    I am setting up a Bayesian analysis using a lognormal distribution with skewed data. I want to estimate the "standard deviations" of samples taken from different bins, where sample-sizes available from some bins are very large, and others are very small. I have reliable prior information...
  4. R

    standard deviation greater than variance, is this ok?

    I am putting together some audit results and it was suggested I present them as mean +/- SD. However there is a significant variance in the results. For example looking at hours it took to achieve a targeted temperature goal : results varied from 0 hours to 11. Using excel I ended up though with...
  5. N

    Standard deviation for final results

    Hi, I have several groups of samples which each group has own average and SD. I use the average of each group to calculate the difference between each group and my reference group using this equation (2^-("Average of the group1" - "Average of the Ref group")). I wonder how can I calculate the...
  6. T

    Are 2 means statistically different?

    Good morning, I was wondering if there is a way to calculate a p value with only the following information: Group A: n=64; Oswestry Disability Index mean = 30 group B: n=62; Oswestry Disability Index mean = 20. I was thinking you could use the Excel difference between 2 means program...
  7. L

    Finding Standard Deviation of Sample Mean

    How do I find the standard deviation of the sample mean? A random sample size of 100 drawn from a population with mean 50 and standard deviation 10 Thanks so much.
  8. V

    Lognormal distribution area within 1 standard deviation

    For a normal distribution I understand that area to left or right of mean within 1 standard deviation is same. What about log normal distribution, is the area to left of mean and to the right of mean within one standard deviation the same also? If not what is the intuition?
  9. T

    Reporting participant numbers for meta analysis

    Hi there, I am hoping you may be able to help me with a query I have. I am conducting a meta analysis on Random Control Trials using REVMAN. I have secondary data I am trying to input.I wanted to know whether participants are added up in each condition if there are multiple trials or whether...
  10. C

    Truncated Data Analysis - Standard Deviation

    It has been too long since I have utilized statistics, so looking for a little simple instructions. Need to verify if my approach is at all correct? I have a problem where we have recorded the volume liquid entering a tank every day for 16 months. I would like to use statistical analysis to...
  11. M

    How does standard deviation change with mathematical operations on the mean?

    Hi everyone, while this question is not homework, I found it to basic to be put in the "research" category. I am comparing nutrient uptake rates of algae under different conditions and have taken samples with three replicates after different times (but also from different beakers each time...
  12. S

    [FactorialANOVA] Which N to use when converting standard error to standard deviation?

    When converting standard error to standard deviation (using the formula SD = SE x SRT of N), I am having trouble with is which N to use - the N of the experimental group (for example), or the number of participants in the overall study. An ANOVA was conducted and I don't have the data but I...
  13. T

    Standard Deviation

    You select a random sample of n = 14 families in your neighborhood and find the following family sizes (number of people in the family). 15, 16, 16, 15, 19, 16, 18, 15, 17,16, 15,17,16, 18 I found the mean family size which is 16.4. To find the mean family size, I added up all of the...
  14. Y

    Coding Group Equivalency on Pre-Treatment Measures for Meta-Analysis?

    Hello- I am constructing a code book for a meta-analysis. I only want to include evaluations where program and comparison groups were reasonably well matched on pre-existing differences in key variables, such as age, prior educational achievement, etc. Any recommendations on what statistic to...
  15. M

    How to divide standard deviation

    Hi, I am developing a model of vehicles traveling regular routes. Assume the length of the path (distance) from each stop to the next is known. Assume the mean travel time is known from each stop on the route to the next. Further assume the standard deviation for the mean travel time from...
  16. B

    Normal Curve & Standard deviation HELP!

    This is my homework question and in my right brained mind can not or the life of me think any further. My only hope is that someone out there in the universe can help my melted brain: Pick a continuous variable (that is, interval or ratio in scale of measurement) that is normally distributed...
  17. K

    Need help interpreting Standard Error and Standard Deviation

    Hello, In another post on SPSS forum I discussed Order effects where I split file on SPSS by order and conducted an independent t test looking at the effects of group on the DV. I found that the original result was only evident in order 1 and not order 2... however on the second order one...
  18. T

    Ordinal or interval survey response analysis (from a convenience sample)

    I have the responses from a survey where people had to provide a rating on a scale from one to five, where five was most positive side of things. I would like to assume it is interval scale where the differences between each point on the scale are the same, as I would like to compute...
  19. A

    Higher standard deviation than the mean

    HI ! Excuse me for my english, my writing is not very good. I want to know what implies or what explains in an excercise when the standard deviation (STD=67) is higher than the mean (M=38), and the histogram behaves like an exponential distribution. Thanks by the way ! :tup: Regards from...
  20. T

    Covariance of two products

    Covariance of two products I am in a stats class and the professor has asked us to calculate the covariance and the standard deviation of the total revenue. I was given the below information: X Unit Price = $10 E[X] = 10,000 Var(X) = 1,000,000 Y Unit Price = $5 E[Y] = 7,000...