Degrees Of Freedom
Bikesh Yadav
Degrees of freedom is a number of
values in a study that has the freedom to the vary. It is a statistical
calculation represent how many values involved in a calculation have the
freedom to vary. It can be calculated to help ensure the statistical validity
of Chi-square est and T-test and these tests are commonly used to compare
observed with data that would be expected to be obtained according to a
specific hypothesis.
The earliest and most basic concept
of the degrees of freedom was noted in the early 1800s, and the modern usage
and understanding of the term were expanded upon first by William Sealy Gosset,
an English statistician in his article “ the probable error of mean”.In his
writing, Gosset did not specifically use the term” degrees of freedom”. he did
however, give an explanation for the concept throughout the course of
developing what would eventually be known students T-distribution. It was the
English biologist and statistician Ronald Fisher began using the term “degrees
of freedom” when he started publishing reports and data on his work developing
chi-squares.
In the degrees of freedom we need to
understand the different kind of like chi-square of test; the test of
independence which asks a questions of relationship, such as, “is there a
relationship between a gender and SAT scores?”. And the goodness of fit test
which asks something like “ if a coin is tossed 100 times, will it come up head
50 times and tails 50 times?” for these tests degrees of freedom are utilized
to determine if a certain null hypothesis can be rejected based on the total
number variables and samples within the experiment. For e.g , let’s suppose a drug
trial is conducted on a group and it is hypothesized that the patients
receiving the drug would show increased heart rates compared to those that did
not receive the drug. The results of the test could then be analyzed to
determine weather the difference in heart rates is considered significant, and
DOF are part of the calculations.
References
https://study.com/academy/lesson/degrees-of-freedom-definition-formula-example.html
https://www.investopedia.com/terms/d/degrees-of-freedom.asp
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