standard deviation

  1. H

    Choosing method for comparing peoples salaries

    I just came to the sad conclusion that I have not been maintaining my statistical skills enough the last years, and therefore I must kindly ask for help in this easy question: How to find standard deviations from variable A for individuals in a group adjusted for effect of variable B? I have a...
  2. I

    I need a push in the right direction, not sure how to attack the problems..

    Hi :) I am new here on the forum and find it a bit difficult to learn the way to go at different statistics/probability - problems. For the most times I am able to figure it out myself doing some research, but the last two problems has got me stuck for a few days. I would be really thankful for...
  3. M

    Hypothetical Statistics Question Regarding Class Curve, Standard Dev, and Mean

    Theoretical question: So say there is a course where if you score two standard deviations below the mean, you will fail the course. The class average will be roughly a 75%, not sure what to set as the baseline for standard dev, and say 150 people are in the class. One person is added to the...
  4. O

    Dividing means and their SD to give confidence limits

    Hi all, I am trying to solve the following elementary stats question, but am not sure how: "10 values were taken to calculate the mean of 'A', and 10 separate values were taken to calculate the mean of 'B': mean A = 73.5 (standard deviation 6.3) mean B = 12.7 (standard deviation 2.7)...
  5. A

    How to find the probability of a sampling error made in estimating the population mean?

    Alright, I have been working on my statistics assignment since Monday and I only have two questions left, dealing with the probability of a sampling error. Unfortunately, I cannot find anything in my notes and only a brief example in my textbook that does not explain the concepts behind the...
  6. hlsmith

    Bayesian Posterior: SD = SE?

    I was curious if the standard deviation in a Bayesian posterior is equal to the standard error?
  7. 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...
  8. 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...
  9. 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...
  10. 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...
  11. 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...
  12. 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.
  13. 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?
  14. 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...
  15. 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...
  16. 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...
  17. 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...
  18. 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...
  19. 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...
  20. 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...