lecture 1 - Types of Data and Data Presentation

What are the main goals of statistics?

To use data to make informed decisions, summarize information, and interpret uncertainty in real-world problems.

What is a population in statistics?

The full set of individuals or items being studied (e.g. all students at a university).

What is a sample in statistics?

A subset of the population used to draw conclusions about the whole group.

What is a parameter?

A numerical summary of a population (e.g. population mean).

What is a statistic?

A numerical summary of a sample (e.g. sample mean).

What is the difference between descriptive and inferential statistics?

Descriptive statistics summarize data; inferential statistics draw conclusions about a population based on sample data.

What is the definition of a variable?

A characteristic or trait that can vary from one observation to another (e.g. age, income, gender).

What are categorical variables?

Variables that represent categories or groups (e.g. gender, car brand); no numerical meaning.

What are numerical (quantitative) variables?

Variables that represent measurable quantities and have numerical meaning (e.g. weight, height).

What is a discrete numerical variable?

A numerical variable that can take only specific values (e.g. number of books).

What is a continuous numerical variable?

A numerical variable that can take any value within a range (e.g. weight, time).

What is a nominal variable?

A categorical variable with no specific order (e.g. eye color, brand).

What is an ordinal variable?

A categorical variable with a natural order or ranking (e.g. satisfaction level: poor, fair, good).

What is an interval variable?

A numerical variable where order matters and intervals are equal, but there's no true zero (e.g. temperature in Celsius).

What is a ratio variable?

A numerical variable where order, intervals, and a true zero all exist (e.g. height, salary).

What is the difference between nominal and ordinal data?

Nominal data has no order; ordinal data has a clear ranking or sequence.

Why do we use graphs in statistics?

To visually represent data clearly and effectively, making trends easier to identify.

What is a frequency table?

A table that shows how often each category or value appears in a dataset.

What is a bar chart used for?

To display categorical variables; bars do not touch.

What is a pie chart used for?

To show proportions or percentages for categorical data.

What is a histogram used for?

To display numerical data by grouping values into intervals; bars touch.

What is a stem-and-leaf plot?

A plot that splits data values into "stem" and "leaf" parts to organize and display numerical data.

What is a scatter plot?

A graph that plots two numerical variables to identify relationships or correlations.

What makes a graph presentation "good"?

Accurate labeling, clear message, consistent scales, minimal clutter, and appropriate type of graph.

What makes a graph presentation "bad"?

Misleading scales, poor labeling, inconsistent bar sizes, or too much info that confuses the viewer.

What is the goal of data presentation?

To communicate data accurately, clearly, and in a way that supports good decision-making.