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# What is POOLED VARIANCE ESTIMATE?

The square-root of a pooled variance estimator is known as a pooled standard deviation. Contents. 1 Motivation; 2 Unbiased least square estimate vs. biased maximum likelihood estimate; 3 Example; 4 See also; 5 References; 6 External links; Motivation.
http://en.wikipedia.org/wiki/Pooled_variance
Best Answer: I can only help with estimate and estimator. Estimator is some mathematical procedure for finding the value of something. Example. If you want to estimate the ...
In statistics, an estimate of a population's variance obtained by combining or pooling data from two or more samples. In the independent samples t test, for example, the squared deviations of the scores from their means in both groups are normally pooled to obtain an estimate of what is assumed ...
http://oxfordindex.oup.com/view/10.1093/oi/authority.20110803100336933
Best Answer: (a) variance = s^2 and variances are additive so: pooled variance, v = (s1)^2 + (s2)^2 = 0.9^2 + 1.2^2 = 2.25 gm^2/dl^2
In short, how do we get the pooled estimate and what are degrees of freedom intuitively? variance mean degrees-of-freedom. share | improve this question. edited Jul 25 '11 at 8:45. Jeromy Anglim 17k 4 42 108 ... For the pooled variance function, ...
http://stats.stackexchange.com/questions/12330/how-to-intuitively-understand-formula-for-estimate-of-pooled-variance-when-testi
In this case, , the pooled estimate of variance can be written , and the unpooled estimate can be written and the difference is , so the pooled estimate is always larger than the unpooled estimate.
http://apcentral.collegeboard.com/apc/members/courses/teachers_corner/49013.html
When you calculate the sample variance using "(sum of squared difference from mean)/N" then it turns out that this gives a biased estimate of the population variance (and it's square-root a biased estimate of the population standard deviation).
Pooled Estimate of the Population Variance (solving for s2pooled).
1. When determining the pooled population variance estimate in a t test for independent means, A. the variance of at least one of the original populations must be known (as opposed to estimated), but the other can be estimated from sample data.
... because we have not taken into account error in our estimation of the pooled standard deviation, but I can live with that. Unequal Sample Sizes. ... many are comfortable with pooled t even when the one sample variance is up to four times the size of the other.
http://core.ecu.edu/psyc/wuenschk/docs30/CI-T-Pooled-Separate.doc
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A pooled variance is simply a weighted average of group variances. The weightings are based upon sample sizes so variances of the larger groups are given more emphasis ... This final formula gives a pooled estimate of the common mean mu.
http://www.isixsigma.com/topic/pooled-variance/
In many cases in statistics, assuming that the variations of multiple groups are equal is both reasonable and convenient. However, because of sampling errors, statisticians ...
http://www.ehow.com/how_7938004_calculate-pooled-estimated-variation.html
In a t-test for independent means, weighted average of the estimates of the population variance from two samples (each estimates weighted by a proportion consisting of its sample's degrees of freedom divided by the total degrees of freedom for both samples).
http://www.blurtit.com/q6783745.html
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Learn what is pooled variance? Definition and meaning on easycalculation math dictionary.
http://easycalculation.com/maths-dictionary/pooled_variance.html
A common task is to estimate the variance of a population from a sample ... Pooled variance; Popoviciu's inequality on variances; Qualitative variation; Sample mean and covariance; Semivariance; Skewness; Taylor's law; Weighted sample variance; Notes
http://en.wikipedia.org/wiki/Population_variance
What is POPULATION VARIANCE ESTIMATE? Mr What will tell you the definition or meaning of What is POPULATION VARIANCE ESTIMATE. Add to favorites. ... When figuring the pooled population variance estimate in a t test for independent means, ...
http://mrwhatis.com/population-variance-estimate.html
Enter your up-to-14 sample sizes, and their sampling estimates for the population’s mean, and variance and then click the Calculate button. ... Variance V(i) > 0: Pooled Mean: Pooled Variance: For Technical Details, Back to: Statistical Thinking for Decision Making.
•What are independent samples? •What is a pooled estimate of variance and why do you need to calculate it? •When do you use a dependent versus an independent sample t test?
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The pooled variance is the average of several group variances, in which each group variance is weighted for the size of the group. Notice that the calculation of the pooled variance is analagous to the calculation of the "pooled" or weighted mean, since "ess-ess" is equal to "en times the variance."
http://ww2.coastal.edu/kingw/psycstats/mathreview/reviewfiles/pooledvar.html
1. What is pooled variance and why is it important? 2. Explain what interval data is and give an example: 3. Write the formula for a problem that has 2 sample populations greater than 30 and the standard deviations are known.
http://brainmass.com/statistics/all-topics/318958
Pooled variance is a method for estimating variance given several different samples taken in different circumstances where the mean may vary between samples but the true ...
Pooled Variance t Test Solution H0: m1 - m2 = 0 (m1 = m2) H1: m1 - m2 ¹ 0 (m1 ¹ m2) a = .05 df = 21 + 25 - 2 = 44 Critical Value(s): Test Statistic Solution Pooled Variance t Test Thinking Challenge You’re a research analyst for General Motors.
Summary Statistics Application Notes for Intel® Math Kernel Library 10.3 Update 12. Estimating a Pooled/Group Variance-Covariance Matrix. Use the VSL_SS_METHOD_1PASS method to compute pooled/group variance-covariance matrices.
http://software.intel.com/sites/products/documentation/hpc/mkl/sslnotes/2_3_estimation_pooled.htm
The estimator, the pooled variance, is Our goal is to estimate the standard deviation of our estimator , so we are estimating the quantity ...
http://mrwhatis.com/the-pooled-estimate-of-the-population-proportion.html
http://varianceformula.com/pooled-variance-formula.html
How to Calculate a Pooled Standard Error. ... How to Calculate Variance From Standard Error. How to Calculate a Pooled Standard Error. Calculate the pooled standard deviation, represented by Sp. ... How to Estimate Costs for an Inground Pool. ...
http://www.ehow.com/how_6050071_calculate-pooled-standard-error.html
What is pooled variance? ChaCha Answer: In statistics, many times, data are collected for a dependent variable, y, over a range of va...
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Pooled estimate variance. Moderators: helmut, Shadow, outermeasure, Ilaggoodly : Page 1 of 1 [ 1 post ] Print view: Previous topic | Next topic : Author Message; herry Post subject: Pooled estimate variance. Posted: Sat, 12 Dec 2009 02:21:48 UTC . Member:
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Calculate the pooled variance for the given data. - Two independent samples were taken, their values were 31.37816 22.34339 22.00059 23.27456 19.58917 19.36148 18.69048 and 20.84991
http://www.docstoc.com/docs/31959368/Statistics-Testing----Calculate-the-pooled-variance
estimate of the variance in either or both of the target populations. Such a “pooled” formula for the SD is shown below: Est. of SD in each pop. (pooled version) or est. of COMMON SD: Formula 1: s p = / [(n 1 - 1) s 2 1 + (n 2 - 1) s 2 2]/ n
http://www.personal.psu.edu/users/d/m/dmr/papers/twosampt.PDF
Pooled Variance Linda Reichwein Zientek & Z. Ebrar Yetkiner. The pooled variance estimates the population vari-ance (σ 2 ) by aggregating the variances obtained from two or more samples.
http://knowledge.sagepub.com/view/researchdesign/n319.xml
Pooled Regression is usually carried out on Time-Series Cross-Sectional data- data ... for independent variables and constant variance across ... assuming constant intercept and slopes. Compared to Fixed Effects Models, Random Effects Models are more complex to estimate ...
http://metriscient.com/pooledreg.htm
If we know that the variances of the two populations are the same, that is, , say, then we use the pooled estimate of variance, ... This we call the minimum variance unbiased estimator/ (MVUE) or the best unbiased estimator/ (BUE), ...
http://2000clicks.com/MathHelp/StatisticsPoint.aspx
Blacksacademy.net Pooled sample estimate &- Population and sample
What is the pooled estimate of the population variance and why do we use it? Home ; Get Tutoring ; Get Paid . Home | Blog | Fees | FAQ; Ask a Question | How Does This Work? | Recent Tutorials | Topics; Upload a Tutorial | See Recent Questions |
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pooled standard deviation A problem often arises when the combination of several series of meas-urements performed under similar conditions is desired to achieve an improved estimate of the imprecision of the process. If it can be assumed
http://old.iupac.org/goldbook/P04758.pdf
Let and be the sample standard deviations constructed from and , respectively. When it is reasonable to assume ``,'' we can construct the pooled sample variance
http://math.tntech.edu/ISR/Mathematical_Statistics/Introduction_to_Statistical_Tests/thispage/newnode19.html
If TRUE then the pooled variance is used to estimate the variance otherwise the Welch (or Satterthwaite) approximation to the degrees of freedom is used. Testimonials. It's very useful to get straight answers for anything you ask.
Best Answer: the pooled variance takes into account the spread of the data between two or more groups. It is used to estimate the variance for a single population under the ...
Key Phrase page for pooled variance estimate: Books containing the phrase pooled variance estimate
http://www.amazon.com/phrase/pooled-variance-estimate
Sample T test calculator calculates the pooled variance (r) by entering the X and Y values.
http://easycalculation.com/statistics/pooled-variance.php
On the other hand, the estimates for the variance were a lot less precise, missing the actual value of the variance by 10 % – 20% ... The pooled estimate decreased to 1.22 g/dl, i.e., a decrease of approximately 40%. Our estimates come with some uncertainty.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1097734/
Calculating the Exact Pooled Variance J. W. Rudmin, Physics Dept., James Madison University Harrisonburg, VA 22807 7/6/2010 version ... V. Advantages of Using the Exact Pooled Variance instead of Using the Mean Variance as an Estimate
http://arxiv.org/pdf/1007.1012
To be strictly accurate, the pooled variance is the variance between the samples added to the variance within the samples. Summary of Standard DeviationThere is an alternative, easy to use formula for standard deviation.
http://suite101.com/article/standard-deviation-calculation-and-pooled-sigma-a99084

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