Displaying Data, Stats and Errors

Question 1

What are the three main ways of collecting data?

Answer 1

• Polls
• Experiments
• Observational studies

Question 2

What is a sample?

Answer 2

A subset of the target population

Question 3

What are the benefits of Random sampling ?

Answer 3

• Ensures equal chance of an individual being chosen from the Target population for sampling
• Avoids Bias
• Allows for the calculations of the likely size of sampling errors
• Increasing the sample size, decreases sampling error

Question 4

Describe precision

Answer 4

-Implies that the value of the statistic is similar in all samples

Question 5

Describe Bias

Answer 5

-Implies that the sample statistic differs systematically

Question 6

Describe the process of systematic random sampling with a random start

Answer 6

• Take the size of the population (n) and the size of the sample (N)
• Calculate the fixed period interval (K=N/n)
• Randomly pick a number between 1 and K
• sample the next individual and the next (individual + K) and so on

Question 7

The process of splitting a sample into groups or subsets and then sampling is called…

Answer 7

Stratified Random sampling

Question 8

Name the 8 types of non-sampling errors

Answer 8

• Selection Bias
• Self-selection Bias
• Interviewer effects
• Non-response Bias
• Question effects
• Survey format/conduction
• Behavioural considerations
• Transferring Findings

Question 9

What is the term for taking a group in an experiment and splitting them up (By age for example)?

Answer 9

Blocking of experimental units

Question 10

What are the two types of observational studies?

Answer 10

• Prospective (for future events)

- Retrospective (for past events)

Question 11

Why might you use a observational study?

Answer 11

If it is impossible, unethical or impractical to conduct an experiment

Question 12

What is a confounding variable?

Answer 12

A factor not accounted for that introduces a difference in outcomes

Question 13

What are the three types of plot sampling?

Answer 13

• Completely random sampling
• Systematic grid, random sampling
• Systematic grid, Systematic sampling with a random start

Question 14

What are the descriptions of response and explanatory variables ?

Answer 14

• Response–> variable we would like to predict

- Explanatory–>variable that helps us explain or predict the response variable

Question 15

What are the two types of quantitative data variables?

Answer 15

• Continuous (infinite number of possible values)

- Discrete (distinct values)

Question 16

What are the two types of qualitative data variables?

Answer 16

• Ordinal (non-numerical, relative values like good, bad)

- Nominal (distinct by name only like green or October)

Question 17

What is the interquartile range ?

Answer 17

The difference between the 75th quantile and the 25th quantile

Question 18

Describe Histograms

Answer 18

• Data partitioned into Bins on the x axis

- Number of points in each bin on the Y axis

Question 19

Describe the shape of a histogram for the following cases:

• Mean>Median
• Mean

Answer 19

• Right skewed
• Left skewed
• Symmetrical

Question 20

What are some of the possible ways to visually display data?

Answer 20

• Histogram
• Box plot
• Violin plot
• Quilt plot
• Bar chart
• Pie Chart

Question 21

What are the lines that extend out of a box plot?

Answer 21

Whiskers and they extend to 1.5 times the interquartile range

Question 22

Describe the Normal distribution

Answer 22

• Bell shaped

- Defined by two parameters, mean and variance

Question 23

Describe what confidence intervals are used to represent

Answer 23

A confidence interval is used to represent a range of values we are either 95 or 99% confident that the true value for the mean or statistical value lies