What is Statistic: Definition and 122 Discussions

A statistic (singular) or sample statistic is any quantity computed from values in a sample that is used for a statistical purpose. Statistical purposes include estimating a population parameter, describing a sample, or evaluating a hypothesis. The average (aka mean) of sample values is a statistic. The term statistic is used both for the function and for the value of the function on a given sample. When a statistic is being used for a specific purpose, it may be referred to by a name indicating its purpose.
When a statistic is used to estimate a population parameter, the statistic is called an estimator. A population parameter is any characteristic of a population under study, but when it is not feasible to directly measure the value of a population parameter, statistical methods are used to infer the likely value of the parameter on the basis of a statistic computed from a sample taken from the population. For example, the mean of a sample is an unbiased estimator of the population mean. This means that the expected value of the sample mean equals the true mean of the population.In descriptive statistics, a descriptive statistic is used to describe the sample data in some useful way. In statistical hypothesis testing, a test statistic is used to test a hypothesis. Note that a single statistic can be used for multiple purposes – for example the sample mean can be used to estimate the population mean, to describe a sample data set, or to test a hypothesis.

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  1. D

    Understanding Statistics and Parameters for Students

    Hey. I just wanted to clear something up. My texbook often refers to statistics and parameters. Is a statistic simply a calculation made on a sample, whereas a parameter is a property of the whole property from which the sample was taken? Thanks in advance, Dan.
  2. M

    Report the test statistic value

    Homework Statement Is the ideal number of children equal to 2 or higher or lower than that? For testing that the mean response from a survey equals 2.0 for the question "What do you think is the ideal number of children to have?" (a). Report the test statistic value and show how it was...
  3. R

    What Is the Probability of Rolling a 3 on a Four-Sided Die?

    Statistic Help!THANKS! Consider the trial on which a 3 is first observed in successive rolls of a four-sided die. Let A be the event that 3 is observed on the first trial. Let B be the event that at least two trials are required to observed a 3. assuming that each side has probability 1/4. find...
  4. R

    Statistic Problems With Quartiles and Standard Deviations

    There are two different problems that I am confused with: 1) The taste of mature cheese is related to the concentration of lactic acid in cheese. Use the concentrations of lactic acid in 30 samples of cheddar cheese on page 15. Well, what's important is that using all the numbers it gave...
  5. B

    Developing a Statistic Test: Can I Have Some Help?

    Hi, I have this problem that I cannot figure out what to do: Given mean 1 =mu 1, variance =sigma1^2. mean 2=mu2, variance =sigma2^2 Test hypothesis Ho: mu1=2*mu2 versus H1: mu1>2*mu2. Develop a statistic test. Can I have some help?
  6. I

    Solving Statistic Problem: Low Tire Pressure & Tread Depth

    Homework Statement when checking tire tread depth at an automobile repair ship, it has been determined that if a tire has low air pressure, there is a 22% probability that its tread depth is less than 1/8 of an inch. on a given day 75 out of 100 tires were found to have a tread depth greater...
  7. L

    Wich test for few events statistic

    Wich is the best hipotesis test if i have very few events? at leats 10-20 events. The chi squared test is not possibile if the expected frequency is less then 10 for every outcome.
  8. E

    Sufficient Statistic: T, S Pairing Explained

    If T(x1...xn) is a sufficient statistic and is paired up with another statistic S(x1...xn) then the (T,S) is still a sufficient statistic i think, correct? But how would I "formally" explain that? thanks.
  9. E

    Parametric function or statistic?

    Which one would you say this is :confused: : E(|x1-x2|) x1, x2, xn - a sample of n values on the underlying random variable... I was thinking this is a statistic :frown:
  10. L

    Can Dr. Easy Reject the Null Hypothesis in the EN-100 Test Analysis?

    Statistic Help! I need some help solving this problem... Dr. Easy saw the scores from the EN-100 test and used the occasion to test the old adage that girls are smarter than boys on subjects tested by ACT. Assume the degrees of freedom for this problem is 28. Dr. Easy did the arithmetic and...
  11. N

    Solving Statistics Questions with Steps: Q1-4

    Statistic Question! I have these four questions I'm having trouble solving... Could anyone write the solutions, but with steps on how they did it so I can possibly learn! Thanks a lot I'm pretty sure they use the binomial or poisson distribution formulas... can't get proper answers 1...
  12. Y

    Statistic student return and forgot it all

    I studied stat couple years ago, and going back again...here goes... THe time needed to complete a final examination in a particular college course is normally distributed with a mean of 80 minutes and a standard deviation of 10 minutes. Assume that the class has students and that the...
  13. L

    Probability and Statistic on Infinite-Dimensional spaces

    Probability and Statistic on "Infinite-Dimensional" spaces Hello..can the theories of Probability and Statistic be generalized to "Infinite-dimensional" spaces?..i mean if there are "probabilistic" phenomenon that include an infinite number of random variables, or include "random functions"...
  14. S

    Can You Calculate a P-Value for Correlation Between Non-Parametric Data?

    I have made a correlation between group A and B and the pearsson coefficient constant, r, is at 0.97. The values are expression levels and hence they are non-parametric. I wonder how can i calculate the p-value of this correlation between group A and B? I know how to calculate the p-value for...
  15. N

    Can someone help me with a Statistic problem?

    Consider a survey of n people asking whether they plan to use Route A or Route B, with an anticipated fraction p choosing Route A. If p = .30, plot the 95% confidence bounds and the expected value of X as a function of n, for n = 50 to n = 800. I have no idea where to start or how to work...
  16. N

    How Do You Calculate Confidence Intervals for Route Preferences?

    Consider a survey of n people asking whether they plan to use Route A or Route B, with an anticipated fraction p choosing Route A. If p = .30, plot the 95% confidence bounds and the expected value of X as a function of n, for n = 50 to n = 800. I have no idea where to start or how to work...
  17. C

    How to measure if a statistic is accurate?

    I am studying the performance statistic of some coding techniques on messages of 380 bits long. I studied it by generating bit sequences randomly and test the performance on each sample. But the sample space is so large (2^380) and practically I can only randomly test about 10^5-10^6 samples...
  18. S

    What kind of statistic methods?

    Okey, i am confused about this matter. I have two different samples. One is 5 untreated/control samples (same kind) and the other is a 50 treated samples (same kind). I wonder what kind of statistic methods i can use to compare the results between them? I don't think that i can use ANOVA...
  19. I

    Probability & Frequency: Definition and Relationship

    Can anybody tell me what is the relationship between probability and frequency and hence what is the meaning of probabilty frequency.
  20. Loren Booda

    Your favorite outrageous statistic

    What do you consider to be the most misleading statistic you have come across or can contrive?
  21. P

    Solve SAT Math & Listening Tests: 90% Confidence Interval

    An SRS of 16 Orange County Schools' juniors had a mean SAT MATH of x = 500; and a Standard Deviation of s=100. We know that the population of SAT Math scores for juniors in the district is approximately normaly distributed. We wish to determine a 90% confidence interval for the mean SAT math...
  22. J

    Statistic HELP Hope someone can

    Statistic HELP! Hope someone can :( I know this is only a physics and math help forum, but I'm pretty sure that most of you have taken a course in statistics... or so I hope. I'll take a long shot anyway... I have a question where I need to find the sample size required in order to get a...
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