Processing and representing data

• What is a database composed of?

  Tables with a collection of data
• What type of data is considered secondary data?

  Data available online and easily accessible
• What should you be able to do with tables in an exam?

  Extract and interpret information from them
• What is a common inconsistency found in tables?

  Percentages not adding up to 100%
• Why do percentages in tables sometimes not add up to 100%?

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

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

  Bivariate data with two variables
• 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 must a pictogram always include?

  A key showing the amount each symbol represents
• What is important when drawing a pictogram?

  Each symbol must be the same size
• How should symbols in a pictogram represent frequencies?

  Numbers that can be easily divided
• What is a characteristic of simple bar charts?

  Bars are equal width with equal gaps
• What does the y-axis represent in simple bar charts?

  Frequency of the data
• What is a vertical line graph similar to?

  A simple bar chart
• What do multiple bar charts compare?

  Two or more sets of data
• How are composite bar charts structured?

  Single bars split into different sections
• 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 any detail
• What do stems and leaves represent in stem and leaf diagrams?

  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 back-to-back stem and leaf diagrams?

  To compare two sets of data sharing the same stem
• What do pie charts display?

  How something is shared or divided
• What do the angles in a pie chart represent?

  Proportion of each category of total data
• How do you calculate the angle for each frequency in a pie chart?

  Multiply by the frequency after dividing 360
• What do comparative pie charts compare?

  Two sets of data of different sizes
• Why should pie charts be drawn in different sizes?

  To avoid misleading comparisons of frequencies
• 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 indicate?

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

  Geographical areas shaded by frequency
• What does darker shading on a choropleth map indicate?

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

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

  Add frequency for that interval to previous CF
• What do CF step polygons use?

  Discrete data
• What do CF curves use?

  Grouped continuous data
• How do you estimate the median from CF diagrams?

  Find the value on the y-axis and read x-axis
• What does the interquartile range (IQR) represent?

  The difference between 75% and 25% values
• How do you estimate frequencies from histograms?

  Use class widths and frequency density