The correlation coefficient ranges from ___ to ___.

-1 to 1

True or False: A correlation coefficient of 0 indicates a strong relationship between two variables.

False. A correlation coefficient of 0 indicates a weak or no relationship.

When the correlation coefficient is close to 1, it indicates that when one variable increases, the other variable tends to ___.

Also increase

Fill in the blank: A correlation coefficient close to -1 suggests a ___ relationship.

Negative

What types of variables can the correlation coefficient be calculated for?

Ordinal, interval, or ratio levels

Riddle: I measure the strength and direction of a relationship but my value ranges from -1 to 1. What am I?

Correlation coefficient

True or False: The correlation coefficient is meaningful for variables measured at the nominal level.

False. It is not very meaningful for nominal level variables.

What is a negative correlation, and provide an example?

A negative correlation occurs when two variables move in opposite directions; as one variable increases, the other decreases. An example is the sale of woollen garments and day temperature.

Fill in the blank: A scatter plot is used to visually represent the ___ and ___ of correlation between two variables.

Strength and direction

True or False: Positive correlation implies that an increase in one variable leads to a decrease in another variable.

False. Positive correlation implies that an increase in one variable is accompanied by an increase in the other.

Riddle: I show the relationship between two things, points scattered across my frame. I'm not a graph for just any purpose, but I help you see correlation's name. What am I?

A scatter plot.

What does Karl Pearson's coefficient of correlation indicate?

It indicates the degree of linear relationship between two variables, providing a precise numerical value.

Fill in the blank: Examples of methods for estimating correlation include scatter diagram, Karl Pearson’s coefficient of correlation, and ___ rank correlation.

Spearman’s

What is an example of a positive correlation?

An example of a positive correlation is the increase in height and weight.

True or False: The closer the points in a scatter plot are to a straight line, the weaker the correlation between the variables.

False. The closer the points are to a straight line, the stronger the correlation.

What is the formula to calculate Karl Pearson’s coefficient of correlation?

Fill in the blank: In the step deviation method, dx represents the deviation of the X-series from the ___ mean.

Assumed

True or False: The assumed mean method requires calculating the sum of deviations from the actual mean.

False. It uses deviations from an assumed mean.

What are the two main methods used to calculate Karl Pearson’s coefficient of correlation?

Actual mean method and Assumed mean method.

Riddle: I’m a measure that shows the strength of a relationship, but I’m not a friend. What am I?

Coefficient of correlation

In the context of correlation, what do the symbols σx and σy represent?

Σx is the standard deviation of the X-series and σy is the standard deviation of the Y-series.

Fill in the blank: The step deviation method is particularly useful when the values of the variables are ___.

Large

What does the variable N represent in the formula for calculating the coefficient of correlation?

N represents the number of pairs of observations.

What is Spearman's rank correlation coefficient primarily used for?

It is used to determine the correlation between variables that may not have a clear or objective measurement, particularly in qualitative variables.

In the formula for Spearman's rank correlation, what does 'D' represent?

'D' represents the rank differences between the paired observations.