Runs

Question 1

The concept of randomness is very pronounced in statistics and probability. It forms the basis of representativeness of a sample to the population from which it is selected. It is for this reason that before we can use a sample statistic to make a probability statement about a population parameter, we expect the sample to be random. The runs test is a procedure employed in testing for

Answer 1

randomness of data.

Question 2

What is a run

Answer 2

Run: a run is a sequence of identical outcomes preceded or followed by a sequence of different outcomes of by none at all.

Question 3

Examples

Answer 3

Examples of Runs:  selection of male and female respondents in a survey, the outcomes of odd and even numbers in numerical data, scores that above or below the median in numerical data, sequences of heads or tails in successive flips of a coin, sequences of favorable or unfavorable attitudes, successive increases of stock prices of a given security (Bullish Run), successive decreases of the prices of a security in the stock market (Bearish run), Arrival of Mass Communication students and other students to CBS 221 class on a Monday Morning etc. 
If the sampling procedure is random, the distribution of runs ® will be approximately normal for a reasonably large sample. The runs formula is given below; in the formula, we expect the number of one type of outcome to be greater than 20. We can use the number of runs to test for randomness by applying the following formulae:

Question 4

R bar=

Answer 4

2n1+n2
———- +1
n1+n2

Question 5

How to get z calxucleted

Answer 5

R-R bar +0.5
——————-
SR

Question 6

How to find sr

Answer 6

Square root of
2n1 n2(2n1n2-n1-n2)
——————————
(n1+n2)^2 (n1 + n2 -1)