LECTURE 8

Question 1

What is correlational analysis?

Answer 1

A method to examine associations between two variables.

Question 2

What is a scatterplot?

Answer 2

A graph showing associations between two variables with each dot representing a data point.

Question 3

What is the direction of association?

Answer 3

Indicates whether the variables are positively or negatively related.

Question 4

What is a positive association?

Answer 4

Larger values of one variable are associated with larger values of the other.

Question 5

What is a negative association?

Answer 5

Larger values of one variable are associated with smaller values of the other.

Question 6

What is the strength of an association?

Answer 6

Reflects how much knowing one variable helps predict the other.

Question 7

What does no association mean?

Answer 7

Knowing one variable gives no information about the other

Question 8

What is the shape of an association?

Answer 8

The pattern of the relationship, such as linear, U-shaped, or inverted U-shaped.

Question 9

What are correlation coefficients?

Answer 9

Descriptive statistics that describe the strength and direction of an association.

Question 10

What is the Pearson correlation coefficient used for?

Answer 10

Linear associations between normally distributed interval or ratio variables.

Question 11

What is the Spearman correlation coefficient used for?

Answer 11

Linear associations between ordinal data or interval/ratio data that is not normally distributed.

Question 12

What is the range of correlation coefficients?

Answer 12

From -1 (perfect negative) to +1 (perfect positive), with 0 indicating no association.

Question 13

What does the numerator in Pearson correlation measure?

Answer 13

Covariance, which indicates the direction of the association.

Question 14

What does the denominator in Pearson correlation measure?

Answer 14

Standardization, allowing interpretation independent of the scale.

Question 15

Do linear transformations affect Pearson correlation?

Answer 15

No, changes like converting cm to m do not impact the coefficient.

Question 16

What is the Spearman correlation based on?

Answer 16

Ranks of data instead of raw values.

Question 17

What is an example of Spearman correlation?

Answer 17

Investigating the relationship between fear of missing out (FOMO) and pub visits.

Question 18

How is Spearman correlation calculated?

Answer 18

By ranking the data and computing the Pearson correlation on the ranks.

Question 19

What is a two-sided test in correlation analysis?

Answer 19

Tests whether the correlation in the population is different from zero.

Question 20

What is a one-sided test in correlation analysis?

Answer 20

Tests if the correlation in the population is positive or negative.

Question 21

How can p-values from a two-sided test be converted for a one-sided test?

Answer 21

Divide the two-sided p-value by 2.

Question 22

Why must one-sided tests be justified?

Answer 22

To avoid accusations of cherry-picking or cheating.

Question 23

What is the line of best fit in scatterplots?

Answer 23

A line that represents the data’s pattern in a correlation.

Question 24

How are correlations reported in scientific articles?

Answer 24

Often in scatterplots or correlation tables.

Question 25

What does r(A, B) = r(B, A) mean?

Answer 25

Correlations are symmetrical; the order of variables does not change the result.

Question 26

What does "Correlation ≠ Causation" mean?

Answer 26

Correlations show associations but not whether one variable causes the other.

Question 27

What is an example of a spurious correlation?

Answer 27

Shoe size correlates with reading ability due to age, not a direct relationship.

Question 28

What is the importance of time order in correlations?

Answer 28

It can sometimes exclude one variable as the causal factor (e.g., temperature rise before film crews arrive).

Question 29

What are degrees of freedom (df)?

Answer 29

The number of observations that are free to vary when computing statistics.

Question 30

How is df calculated in correlation tests?

Answer 30

df=n−2, where n n is the sample size.

Question 31

What is the difference between a two-sided and one-sided correlation test?

Answer 31

Two-sided tests for any difference, while one-sided tests for a specific direction.

Question 32

What is the main use of scatterplots?

Answer 32

Visualizing the strength, direction, and shape of associations.

Question 33

How are correlation coefficients visualized?

Answer 33

In scatterplots or tables with associated p-values.

Question 34

What does p < 0.05 indicate in correlation tests?

Answer 34

The result is statistically significant.

Question 35

How are correlation coefficients reported?

Answer 35

As r, with up to 3 decimal places, bounded between -1 and +1.

Question 36

What is the role of p-values in reporting correlations?

Answer 36

They indicate whether the correlation is statistically significant.

Question 37

How does practice improve correlation interpretation?

Answer 37

By identifying patterns in scatterplots and computing correlations.