Task 4: Consensus?

Question 1

Two variables on the same case are associated if..

Answer 1

knowing the values of one of the variables tells you something about the other variable that you would not know.

Question 2

x = response variable measures

Answer 2

an outcome.

Question 3

y = explanatory variable ..

Answer 3

explains or causes changes in the response variable.

Question 4

A scatterplot shows

Answer 4

the relationship between the quantitative variables measured on the same individuals (horizontal and vertical axis).

Question 5

When examining a scatterplot, look for:

Answer 5

1. Overall pattern
2. Striking deviations
3. Outliers.

Question 6

The overall pattern is being described by:

Answer 6

1. Form (linear transformation)
2. Direction (positive or negative association)
3. Strength of a relationship.

Question 7

The strength of a relationship shows ..

Answer 7

how closely the points follow a clear form.

Question 8

Direction / association between 2 variables can be:

Answer 8

1. Positive ( A increases => B increases)

2. Negative ( A increases => B decreases)

Question 9

If the relationship does not make sense, then..

Answer 9

you need additional analyses.

Question 10

To add categorical variables to a scatterplot one must..

Answer 10

use different plot colours or symbols for each category.

Question 11

Correlation r measures..

Answer 11

the direction and strength of the relationship between the quantitative variables.

Question 12

Characteristic of the correlation r:

Answer 12

1. r does not change when we change the units of measurement ;
2. r is not resistant ;
3. r is not a complete description ;
4. r measures only linear relationships.

Question 13

The two-way table of counts organises ..

Answer 13

data about two categorial variables and is used to summarise large amounts of data by grouping into categories (row and columns).

Question 14

To find the joint distribution..

Answer 14

divide each cell entry by the total sample size.

Question 15

To find the marginal distribution..

Answer 15

divide each total by the final total.

Question 16

The conditional distribution means that ..

Answer 16

we condition on the value of one variable and calculate the distribution of the other variable, by looking at only one column at a time and computing the distribution for every entry.