CHAPTER 2 Flashcards
what is a database?
- a collection of information
what is a two- way table?
- shows information in two categories
what is data that has two variables called?
- bivariate data
what is a pictogram?
- uses symbols or pictures to represent a number of items
what is a bar chart?
- bars are equal width
- height represents frequency
what is a multiple line graph?
- similar to a bar graph but uses lines instead of bars
what is a multiple bar chart?
- they have more than one bar for each class
- a key shows what each bar represents
- easy to compare the frequencies of each category
what is a composite bar chart?
- each bar shows the total frequency for different components of that group
- frequencies stacked on top of one another
what is a stem and leaf diagram?
- shows numerical data split into ‘stem’ and ‘leaves’, the numbers are written in order
- make sure to use a key- shows how to read numbers
what does a stem and leaf diagram show?
- shows the shape of the data distribution in the same way which a bar chat does but you can still see the original data values
what does a back -to- back stem and leaf diagram show?
- two sets of data with the same stem
- smallest values on each row are nearest to the stem
what is a pie chart?
- a way of displaying data when you want to show how something is shared or divided
- uses area to represent frequency
- angles in a pie chart add up to 360
what does the area of each sector show in a pie chart?
- proportional to the frequency it represents
what is the area of the whole pie chat proportional to?
- the total frequency
what can comparative pie charts be used for?
- to compare two sets of data with different frequencies
- areas of the two circles should be proportional to the total frequency
how do you compare frequencies in a comparative pie chart?
- compare areas
how do you compare proportions in a comparative pie chart?
- compare individual angles
what is a population pyramid?
- similar to bar chart and stem and leaf diagram
- used to show the age group I a population, usually divided by gender
what is a choropleth map?
- used to classify regions of a geographical area
- a key shows what each shade represents
- can be a diagram rather than an accurate map
what data is used in a histogram?
- continuous
- meaning there are no gaps between the bars
frequency density equation:
- frequency density= frequency/ class width
what is a frequency polygon?
- joins the midpoints of the tops of the bars of a histogram with straight lines
- may be drawn with or without a histogram
what is the cumulative frequency?
- running total of frequencies
what can you draw when the cumulative frequency data is discrete?
- cumulative frequency step polygon
- plot the cumulative frequencies against the upper class boundaries
what can you draw for grouped continuous data?
- cumulative frequency diagram
- plot the cumulative frequencies against the upper class boundary
what can cumulative frequency diagrams be used for?
- to estimate or predict other values
what is the shape of a distribution?
- the shape of a distribution is the shape formed by that bars of a histogram, or by a frequency polygon
different kinds of skew:
- positive
- symmetrical/ no skew
- negative
what does a symmetrical skew mean?
- most of the data values are at the lower end
- right foot
what does a negative skew mean?
- most of the data values are at the upper end
- left foot
