The Scientific Method & Statistical Analysis

Question 1

What is the definition of the Scientific Method?

Answer 1

A systematic investigation towards increasing the sum of human knowledge

Question 2

What is a research hypothesis?

Answer 2

A research hypothesis is a statement that proposes a possible explanation to some phenomenon or event

Question 3

What is a characteristic of a good hypothesis?

Answer 3

A good hypothesis must be testable (falsifiable/refutable)

Question 4

Research Question: You are interested in understanding what causes leaves to change colour?

Which of the following hypothesis is testable?

A. Temperature may cause leaves to change colour

B. Leaves change colour as little invisible elves want them to

Answer 4

A as B cannot be rejected because there is no way to measure the activity of little invisible elves

Question 5

What do good hypotheses often contain?

Answer 5

Good hypotheses often contain at least two variables and their (causal) connection

Question 6

What are the two main types of research designs for collecting data?

Answer 6

• experimental research
• observational research

Question 7

What is experimental research?

Answer 7

Experimental research involves willfully manipulating (independent/predictor/treatment) variables to observe the outcome on your response (dependent) variable.

Question 8

What is observational research?

Answer 8

Observational research involves studying the response variable in ‘in situ’ without any direct manipulation of independent/predictor variables

Question 9

What is the independent and dependent variable in this research question:

How does biodiversity change with decreasing latitude?

Answer 9

Dependent variable: Butterfly species no.
Independent variable: Latitude

Question 10

What is the independent and dependent variable in this research question:

Does dosage of an antibiotic lead to more resistance?

Answer 10

Dependent variable: Bacterial survival
Independent variable: Dose levels of antibiotic

Question 11

What is the independent and dependent variable in this research question:

Is a particular gene involved in eye development ?

Answer 11

Dependent variable: Eyes present or absent
Independent variable: is the gene on or off?

Question 12

What is sampling in research design?

Answer 12

Sampling in research design is the process of selecting a subset of individuals or units from a larger population to study

Question 13

Why do we have to sample from a population?

Answer 13

We have to sample from a population because it is often impractical or impossible to collect data from every individual in the population

Question 14

Why does the sample have to be random?

Answer 14

The sample has to be random to avoid bias and ensure that every individual or unit in the population has an equal chance of being selected

Question 15

What are some different approaches to random sampling?

Answer 15

Different approaches to random sampling include:
- simple random sampling
- stratified random sampling
- cluster random sampling
- systematic random sampling

Question 16

Why is random assignment used?

Answer 16

Random assignment is needed in experimental studies to ensure that each participant has an equal chance of being assigned to different treatment groups.

Question 17

Why may random sampling not be useful in an experimental study?

Answer 17

Random sampling may not be useful in an experimental study if the sample is already limited to a specific population that has met certain inclusion criteria

Question 18

What is Random Sampling?

Answer 18

Random Sampling is a research design sampling method in which every element of the population has an equal chance of being selected

Question 19

What factors determine the choice of sampling method?

Answer 19

The choice of sampling method depends on:
- your population
- budgetary constraints

Question 20

What is the objective of using Random Sampling methods?

Answer 20

Help minimise any errors caused by chance, bias, or confounding when making inferences

Question 21

What is the significance of variability in statistics?

Answer 21

Refers to the amount of dispersion or spread of data around the mean or average. The degree of variability can provide important information about the data and help in drawing meaningful conclusions.

Question 22

Can the number of bricks eaten last week be used in statistical analysis?

Answer 22

No as it is not a relevant or meaningful variable

Question 23

Can the number of grapes eaten last week be used in statistical analysis?

Answer 23

Yes as it is a relevant and meaningful variable

Question 24

Which of the following are Statistical Questions:

How much does my pet grapefruit weigh?
What was the average score on the essay on the Practising Scientist last year?
How many teeth does my mother have?
How much time do members of family spend on their phones (screen time) at dinner?
How many times have I watched Lord of the Rings?

Answer 24

statistical questions:
- What was the average score on the essay on the Practising Scientist last year?
- How much time do members of family spend on their phones (screen time) at dinner?

not statistical questions:
- How much does my pet grapefruit weigh?
- How many teeth does my mother have?
- How many times have I watched Lord of the Rings?

Question 25

What is the difference between descriptive and inferential statistics?

Answer 25

Descriptive statistics: involves summarising and exploring a collection of data, either graphically or numerically.
Inferential statistics: involves estimating parameters and their confidence limits, as well as hypothesis testing.

Question 26

What are some examples of descriptive statistics?

Answer 26

• measures of central tendency (e.g., mean, median, mode)
• measures of variability (e.g., range, standard deviation)
• graphical displays (e.g., histograms, box plots, scatter plots)

Question 27

What are some examples of inferential statistics?

Answer 27

• hypothesis testing (e.g., t-tests, ANOVA, regression analysis)
• confidence interval estimation
• model selection

Question 28

What are the two types of variables in data?

Answer 28

• numerical
• categorical

Question 29

What are numerical variables?

Answer 29

Variables that
- take on numerical values
- sensible to perform arithmetic operations on
- quantitative

Question 30

What are some examples of numerical variables?

Answer 30

• age
• height
• weight
• income
• temperature

Question 31

What are categorical variables?

Answer 31

Variables that
- take on a limited number of distinct categories
- not sensible to perform arithmetic operations with these categories (but can be identified with number)
- qualitative variables

Question 32

What are some examples of categorical variables?

Answer 32

• gender
• ethnicity
• occupation
• education level
• favorite colour

Question 33

What are the subtypes of numerical variables?

Answer 33

• continuous
• discrete

Question 34

What is a continuous variable?

Answer 34

A numerical variable that can take on any value within a given range

Question 35

What is a discrete variable?

Answer 35

A numerical variable that can only take on specific, distinct values, often represented by integers

Question 36

What are the subtypes of categorical variables?

Answer 36

• regular categorical
• ordinal
• binary

Question 37

What is a regular categorical variable?

Answer 37

A categorical variable that can take on one of several distinct categories, but these categories have no inherent order or ranking

Question 38

What is an ordinal variable?

Answer 38

A categorical variable in which the categories have an inherent ordering or ranking

Question 39

What is a binary variable?

Answer 39

A categorical variable that can take on only two categories, such as
- yes or no
- true or false
- male or female

Question 40

How can errors in numeric data be identified and corrected in Excel?

Answer 40

• plot each numerical variable as a column chart or scatterplot and look for outliers
• row number will be on the x-axis, so you can go and check the value
• can also sort each numerical column and look at the extreme ends to identify potential errors
• once errors are identified, they can be corrected directly in Excel

Question 41

What is alphanumeric data?

Answer 41

Data that consists of both letters and numbers

Question 42

How can errors in alphanumeric data be identified and corrected in Excel?

Answer 42

• sorting and checking, but this method may miss subtle differences such as case changes, missing letters, and spaces
• Pivot Tables: quickly identify and correct errors

Question 43

How are missing values represented in Excel?

Answer 43

By blank (empty) cells

Question 44

What code is used for missing values in R?

Answer 44

In R, the code NA is used for missing values and should not be used for anything else

Question 45

What are the $ sign rules?

Answer 45

$A1 = column A, but different row
A$1 = row 1, different column
$A$1 = same cell