Question

Question 5. CORRELATION

a. Describe the purpose of the Correlation technique

b. State at least two research problems or question that requires the use of the Correlation technique

c. Identify, describe and test the assumptions related to the Correlation technique

d. State examples of the Correlation technique outcomes

e. State examples of the Correlation technique report results

Answer 1

(a)

The correlation is one of the common and most useful tool in statistics. In our day today life we come across various situations, in which we observe relationship between some variables. Correlation measures the closeness of the relationship between the variables. In other words Correlation is a statistical measure that indicates the extent to which two or more variables fluctuate together. If two variables deviate in the same direction, i.e. if the increase in one results in a corresponding increase in the other, correlation is said to be direct or positive. But if they constantly deviate in opposite directions, i.e. if increase in one results in corresponding decrease in the other, correlation is said to be diverse or negative. In other words Correlation is a term that refers to the strength of a relationship between two variables.

For example, the correlation between

(i) Wages and price index.

(ii) Height of father and son

(b)

The two research problems that require correlation technique.

1. Researcher want to know whether education and emotional competence scores have association.

2. Researcher want to know whether Price of cell phone and demand are associated to each other,

(c)

Assumptions:

1. Level of measurement Assumption:

Level of measurement refers to each variable. For a Pearson correlation, each variable should be continuous. If one or both of the variables are ordinal in measurement, then a Spearman correlation could be conducted instead.

2. Linearity Assumption

Linearity refers to the shape of the values formed by the scatterplot. For linearity, a “straight line” relationship between the variable should be formed. If a line were to be drawn between all the dots going from left to right, the line should be straight and not curved.

(d)

(e)

From correlation between height of son's and height of father's, correlation coefficient is 0.99, thus we see highly positive correlation between height of son's and height of father's. Increasing height of father's lead to increasing height of son's.