standard deviation

  1. B

    Probability Distribution of Cars Sold

    Hi, I'm struggling with where to go with the following problem: The probability distribution below is representative of x, the number of cars sold within a single day. x = 0, 1, 2, 3, 4 P(x) = 0.1, 0.4, 0.3, 0.2 I calculated the standard deviation and mean, which I believe 0.917 and 1.6...
  2. S

    Standard deviation from ANOVA-table

    I am trying to find an estimate for σ , based on the ANOVA-table under, but I dont know where to start. Is it possible to find the estimate for σ from the residual standard error? if so, how?
  3. S

    Calculating confidence intervals for monthly data

    Hello, I am currently working with monthly data and I try to calculate confidence intervals for the monthly average. I have data from from 2010 to 2019 and there seems to be some seasonality. The statement I want to make, is: In december 2020, we expect a value of x which lies with a certainty...
  4. BeaT

    Standard Deviation problem.

    Hi everyone, I wonder if anyone out there would help me solving this one? - I've struggle with it for a few days now. Thank you so much! Bea.
  5. J

    Does adding data to a data set affect the standard deviation?

    Hi, quite a basic question here but I can't find a solid answer. If I had a data set of 10 points, and I chose to add 4 new data points to it for example, can I use the same original standard deviation? Or must I re-calculate it? Is it possible to add the new data points with a specific number...
  6. A

    Rookie finance question: standard deviation

    Hi Im kinda new to statistics and would very much appreciate some help. I have finally understood the standard deviation formula and the reason behind every step/calculation. But..lets talk about stock market. a) why does the stock market write s.dev in percentage? I had the impression that...
  7. J

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  8. M

    Can I apply Standard Deviation and IQR on daily work hours?

    Hi, I'm wondering if we could apply standard deviation or IQR on our daily log on time? I have a dataset with many machine ID that has many log in records for entire month. I have removed the weekend data and left with log in data of over 1000 machines. From the dataset, each machines has...
  9. A

    Calculating SEM in test-retest study (ICC)

    Hi! I am involved in the writing of a thesis, where two raters are running a test-retest study to test the intra- and inter-rater reliability of a clinical test. Here the Standard Error of Measurement (SEM) needs to be reported, and the following formula should be used: SEM=SD x √(1-ICC). I...
  10. M

    Estimated standard error

    Why is it ok to estimate the population variance with the sample variance formula (i.e. the unbiased estimate of the variance). I understand how we can build a confidence interval using the central limit theorem and the following formula . But, the unbiased estimate of the variance means that...
  11. CharlotteSirot

    Test temporal change in standard deviation

    Very dear geeks :cool:! I am new in this forum. I am a french post-doc in marine ecology and I am especially interested in trophic relationships. I am currently analyzing time series. I have to admit that time series are definitely one of my strongest Achilles heels, I am actually afraid of...
  12. B

    Aggregate precision of a measurement instrument based on a sample of measurements whose true errors are known

    I want to estimate the accuracy and precision of aggregate data from an instrument that measures a variable that fluctuates over time by comparing a sample of its measurements to concurrent measurements made by a reference instrument. For this purpose, assume that the reference instrument...
  13. B

    Standard deviation of three producttypes

    Hi guys!. I need some statistics help here. I have three producttypes; Plates, spoons and mugs This is what i know Spoons: Mean = 565,87 Variance = 50677,28 Standard Deviation = 225,12 Correlation with plates= 0,8394 Correlation with mugs = 0,8271 Plates: Mean = 1806,83 Variance...
  14. D

    Back-calculation (a posteriori) of the minimum sample size for a mechanical experiment

    Hello, I want to back-calculate the minimum sample size for a mechanical experiment. I have a known mean and standard deviation of a statistical population. From the statistical population I chose two samples with means and standard variances I could estimate. My question is: How can I...
  15. J

    Calculation of overall ranking from mean, SD, and Z score

    Hey everyone, I was hoping someone could help me. Im applying for a job, and am trying to work out my overall ranking in two seperate exams so that I can include this in the application. Could someone please tell me if my calculation is correct? I have attached the file with my calculation...
  16. D

    Statistically significant difference between distributions only knowing the mean and std dev?

    I have 3 specimens (A, B & C) and 5 sets of observations from A & B but only 4 from C. Each observation has been reported as a mean & a standard deviation. I do not have access to the underlying data. I am curious about whether the samples are statistically different from each other as far as...
  17. 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...
  18. 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
  19. 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...
  20. 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...