To take a simple case, let's suppose you have a set of pairs (x1, y1), (x2, y2), ... (xn, yn). You have obtained these by choosing the x values and then observing the corresponding y values experimentally. This set of pairs would be called a sample.
For whatever reason, you assume that the y's and related to the x's by some function f(.), whose parameters are, say, a1, a2, ... . In far the most frequent case, the y's will be assumed to be a simple linear function of the x's: y = f(x) = a + bx.
Since you have observed the y's experimentally they will almost always be subject to some error. Therefore, you apply some statistical method for obtaining an estimate of f(.) using the sample of pairs that you have.
This estimate can be called the sample regression function. (The theoretical or 'true' function f(.) would simply be called the regression function, because it does not depend on the sample.)
What is the difference between the population and sample regression functions? Is this a distinction without difference?
I want to develop a regression model for predicting YardsAllowed as a function of Takeaways, and I need to explain the statistical signifance of the model.
Regression analysis is based on the assumption that the dependent variable is distributed according some function of the independent variables together with independent identically distributed random errors. If the error terms were not stochastic then some of the properties of the regression analysis are not valid.
Alpha is not generally used in regression analysis. Alpha in statistics is the significance level. If you use a TI 83/84 calculator, an "a" will be used for constants, but do not confuse a for alpha. Some may, in derivation formulas for regression, use alpha as a variable so that is the only item I can think of where alpha could be used in regression analysis. Added: Though not generally relevant when using regression for prediction, the significance level is important when using regression for hypothesis testing. Also, alpha is frequently and incorrectly confused with the constant "a" in the regression equation Y = a + bX where a is the intercept of the regression line and the Y axis. By convention, Greek letters in statistics are sometimes used when referring to a population rather than a sample. But unless you are explicitly referring to a population prediction, and your field of study follows this convention, "alpha" is not the correct term here.
Her regression is smoking.
The sample regression function is a statistical approximation to the population regression function.
What is the difference between the population and sample regression functions? Is this a distinction without difference?
In a regression of a time series that states data as a function of calendar year, what requirement of regression is violated?
1. PRF is based on population data as a whole, SRF is based on Sample data 2. We can draw only one PRF line from a given population. But we can Draw one SRF for one sample from that population. 3. PRF may exist only in our conception and imagination. 4. PRF curve or line is the locus of the conditional mean/ expectation of the independent variable Y for the fixed variable X in a sample data. SRF shows the estimated relation between dependent variable Y and explanatory variable X in a sample.
There is no such term. The regression (or correlation) coefficient changes as the sample size increases - towards its "true" value. There is no measure of association that is independent of sample size.
AnswerA sample is a subset of a population. Usually it is impossible to test an entire population so tests are done on a sample of that population. These samples can be selected so that they are representative of the population in which cases the sample will have weights, strata, and clusters. But usually people use random samples. So it's not that the line is different, it's that the line comes from different data. In stats we have formulas that allow a sample to represent a population, if you have the entire population (again unlikely), you wouldn't need to use this sample formulas, only the population formulas.
I want to develop a regression model for predicting YardsAllowed as a function of Takeaways, and I need to explain the statistical signifance of the model.
In fitting a logistic regression, as in applying any statistic method, the required sample size depends on the level of dispersion in the population and the quality of the statistics that you are prepared to accept. Usually there will be some information available somewhere (in the literature, say, or from colleagues) suggesting what level of variability to expect in data that is collected. This can be used to simulate some data sets and the logistic regression results that would arise from them. By varying the sizes of the data sets you can make a judgement. Once you have collected your first sample and fit the actual logistic regression to it you will have a much better idea how much data is actually required for useful estimates.
Sample
Regression analysis is based on the assumption that the dependent variable is distributed according some function of the independent variables together with independent identically distributed random errors. If the error terms were not stochastic then some of the properties of the regression analysis are not valid.
sab hum hi batayenge to tum kya jhak maaroge...
y=a+bx+e sample regression model differentiate between y bar and E(Y)?