LM 01

Question 1

Definition of a data matrix

Answer 1

A convenient way to store data. Examples included tables and spreadsheets. Your trout is a unique case (observational unit) . Each column corresponds to a variable.

Question 2

Types of variables

Answer 2

Numerical or categorical.

Question 3

Classifications of numerical variables

Answer 3

Numerical variables can be discreet or continuous.

Question 4

Classifications of categorical variables

Answer 4

Categorical variables can be ordered or nominal.

Question 5

Explanatory and response variables

Answer 5

Explanatory variables might affect response variables. For example hours of study per week might affect GPA.

Question 6

Types of data collection

Answer 6

Observational studies. Researchers collected data passively they merely observe.
Experiments: researchers actively control the data collection trying to establish causation

Question 7

Sample versus population

Answer 7

Sample is a subset of population. Population is people sample is a group of selected people.

Question 8

Simple, random sample.

Answer 8

Randomly selected from population. Example cars passing through intersections in Kelowna.

Question 9

Stratified sample

Answer 9

Cases grouped into strata, then a simple random sampling.

Question 10

Cluster sample.

Answer 10

Divided into clusters and sample all of an individual cluster. Example all cars at three intersections.

Question 11

Multi stage sampling

Answer 11

Clusters are sampled for example, cars are randomly sampled at three intersections

Question 12

Scatterplot

Answer 12

Way to provide case by case view of data. can visualize relationship between two numerical variables

Question 13

Dot plot

Answer 13

Visualize one numerical variable.

Question 14

Histograms

Answer 14

Provides a view of the data density. I.e. the data distribution.

Question 15

Unimodal

Answer 15

A single prominent peak.

Question 16

Bimodal/multimodal

Answer 16

Several prominent peaks

Question 17

Uniform

Answer 17

No apparent peaks

Question 18

Right skewed

Answer 18

Tale of the cat on the right hand side

Question 19

Left skewed

Answer 19

Tale of the cat on the left-hand side.

Question 20

Small variance

Answer 20

Sharpen, narrow peak

Question 21

Large variance

Answer 21

Wide peak

Question 22

Deviation

Answer 22

Distance from the mean

Question 23

How to draw a box plot

Answer 23

1) draw a thick line for the median, Q2
2) draw a rectangle with bound Q1 and Q3
3) draw a dotted line for Q1 -1.5 IQR and Q3 +1.5 IQR
4) label, outliers and draw T-shirt, upper and lower whiskers. Only goes as far as either the highest or lowest points.

Question 24

Robust statistics

Answer 24

Mean and IQR are more robust than mean and standard deviation.

Question 25

Common practice

Answer 25

Symmetric distributions you use mean and standard deviation.
Skewed distributions you use median and IQR .