standard deviation

  1. B

    Hypothesis testing

    Hey guys, This is my first thread on this forum so please bare with me as I try to be as concise as possible, I'll then write down my questions at the end of the thread. I'm working on some class notes, and stumbled upon this problem that confuses me on some point: "The drying time of a...
  2. R

    Normal Distribution of multiple Std.Dev´s and Means

    Is there a way to calculate the Normal Distribution of a set of multiple Standard Deviations (SD) and Means (µ)? I am afraid I do no have Access to the raw data from which the SD´s and µ´s were calculated. Many thanks in advance
  3. H

    Statistical power of two dataset

    Hi All, I would like to inquire how to decide whether Dataset A or Dataset B would be reliable based on their coefficient of variation, number of data points and mean value. What kind of factors could be considered? I am not searching for the direct answer but rather to jump into the...
  4. W

    how to get a normalized daily standard deviation from erratic data

    Hi, I use Excel to analyze data. On one of my workbooks, I have about 30,000 rows of intraday data. Sometimes I might have 0 datapoints on a particular day, some days I might have 15 datapoints, and other days 20 datapoints. On average, I have about, 5,500 datapoints over the period of a...
  5. G

    Average and standard deviation

    Hi All, I am measuring the height of a tank over time to calculate the flux. -F is the volume of tank F -On every time point, the volume is measured 3 times (since the way of measuring is quite fault sensitive) So F has an average and a standard deviation. -Flux: (F(t)−F(t−1))/dt, in which dt...
  6. 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...
  7. 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...
  8. 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...
  9. 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)...
  10. 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...
  11. hlsmith

    Bayesian Posterior: SD = SE?

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