SDA: Continuous Data Relationships

Question 1

What data are scatterplots used for?

Answer 1

Ratio/Interval data

Used to identify linear relationships

Question 2

What are the 5 main relationships that can be identified?

Answer 2

1. Strong Positive
2. Strong Negative
3. Weak, dispersed (+ve or -ve)
4. No relationship
5. Non-linear (+ve or -ve)

Question 3

What is the Pearson Product Moment Correlation Coefficient (PPMCC)?

Answer 3

A parametric statistic used to identify the relationships between two variables

Question 4

When is the PPMCC used?

Answer 4

With interval/ratio data

When it is assumed both variables are normally distributed

Question 5

How is the statistical significance evaluated for the PPMCC?

Answer 5

Either reference to p-values or comparison with a table of critical values

Question 6

What is the range of results for a PPMCC?

Answer 6

-1 to 1
-1 = perfect negative
1 = perfect positive
0 = no relationship

Question 7

When is the Spearman Rank Correlation Coefficient (SRCC) used?

Answer 7

Measuring the statistical significance of a correlation between ORDINAL data

Question 8

What are the advantages of SRCC over PPMCC?

Answer 8

Avoids assumptions that must be achieved for use of PPMCC

Easier to compute

Question 9

What is the disadvantage of SRCC?

Answer 9

The use of ordinal data poses problems when using ranked data with several observations with the same rank value