chapter 2

• What is a database?

  A collection of data organized in tables
• What type of data do databases typically contain?

  Real-life statistics
• What should you be able to do with tables in an exam?

  Extract and interpret information
• Why might percentages in tables not add up to 100%?

  Due to rounding errors in calculations
• How should you think about data in tables during an exam?

  In terms of real-life situations
• What type of data do two-way tables contain?

  Bivariate data
• How do you find missing values in two-way tables?

  Start with the row or column with one missing
• What should you ensure when comparing two-way tables?

  Grand totals for rows and columns match
• What do pictograms use to represent data?

  Pictures or symbols
• What is essential when drawing a pictogram?

  Each symbol must be the same size
• How can you represent frequencies in a pictogram?

  By drawing parts of symbols for fractions
• What is a simple bar chart characterized by?

  Equal width bars and equal gaps
• What does a vertical line graph resemble?

  A simple bar chart with lines
• What is the purpose of multiple bar charts?

  To compare two or more data sets
• How are composite bar charts structured?

  Single bars split into sections for categories
• How do you calculate the frequency of components in composite bar charts?

  Subtract upper frequency from lower frequency
• What do stem and leaf diagrams help organize?

  Data without losing detail
• What do stems and leaves represent in a stem and leaf diagram?

  Stems are multiple digits, leaves are single digits
• How should leaves be arranged in a stem and leaf diagram?

  In order from smallest to largest
• What is the purpose of a pie chart?

  To show how data is divided into categories
• What do the angles in a pie chart add up to?

  360 degrees
• How do you calculate the angle for each category in a pie chart?

  Multiply the frequency by the angle per unit
• What do comparative pie charts help compare?

  Two sets of data of different sizes
• What do population pyramids show?

  Distribution of ages in a population

  
• What does a pyramid shape in a population pyramid indicate?

  A higher proportion of younger people
• What does an upside-down pyramid in a population pyramid suggest?

  A larger proportion of older people
• What do choropleth maps use to represent data?

  Shading of geographical areas
• What does darker shading on a choropleth map indicate?

  A higher frequency for that area
• What is cumulative frequency?

  A running total of frequencies
• How do you calculate cumulative frequency for a class interval?

  Add frequency for that interval to previous CF
• What is the purpose of CF step polygons?

  To represent discrete data
• How do you plot points for CF curves?

  Using upper bounds of class intervals
• What do histograms represent?

  Continuous data from grouped frequency tables
• What is the difference between equal and unequal class widths in histograms?

  Equal widths have no gaps, unequal reflect density
• What is the shape of a distribution?

  The form created by the data diagram
• What are frequency polygons similar to?

  Histograms with equal class widths
• What common errors occur with frequency polygons?

  Midpoints not used or points not joined
• What can make diagrams misleading?

  Shape, axes, and scales
• What is a common issue with pictograms?

  Symbols must be the same size and key needed
• How can 3D charts be misleading?

  They distort parts, making values hard to read