Lecture 2a - Descriptive Stats I

What is a frequency distribution?

A frequency distribution shows how the frequencies are distributed over various categories.

How is relative frequency calculated?

Relative frequency is calculated as the frequency of a category divided by the total number of observations (n).

What graphical representation is used for categorical data?

Bar charts and pie charts are used for graphical representations of categorical data.

What does a pie chart represent?

A pie chart represents relative or percentage frequencies and frequency distributions of categorical data.

What is the purpose of grouped frequency distribution?

Grouped frequency distribution organizes data into intervals or classes to summarize data points.

How do you determine the class width in frequency distribution?

Class width is determined by the formula: width = (largest number - smallest number) / desired number of intervals.

What is the difference between cumulative frequency and cumulative relative frequency?

Cumulative frequency shows the number of observations with a value less than or equal to the upper limit of each class, while cumulative relative frequency shows the proportion of observations with a value less than or equal to the upper limit.

What indicates a symmetric histogram?

In a symmetric histogram, the left tail is a mirror image of the right tail.

What defines left skewness in a histogram?

A left-skewed histogram shows the majority of values on the higher end, with a longer tail on the left.

What defines right skewness in a histogram?

A right-skewed histogram shows the majority of values on the lower end, with a longer tail on the right.

How are stem-and-leaf plots useful?

Stem-and-leaf plots show the actual values of a data set while maintaining their rank order and the shape of the distribution.

What does the term 'leaf unit' refer to in stem-and-leaf plots?

Leaf unit is the value each leaf represents, such as 1, 0.1, or 10, depending on how the data is represented.

What type of data visualization uses rectangular bars with no spaces in between?

A histogram uses rectangular bars of equal width with no spaces between them to illustrate quantitative data.

What is an example of cumulative percentage frequency?

The last entry of a cumulative percentage frequency distribution equals 100%.

How can data be displayed using a dot plot?

In a dot plot, each data value is represented by a dot placed above the corresponding value on the X axis.