S1.1 Classifying and Representing Data Flashcards
Understand the planning and management of data collection, classification and representation of data
Data
Classifying Data
Data can be classified into into two broad types.
Categorical data is represented by words or symbols.
Numercial Data is represented by quantities or numbers.
Categorical Data
Categorical data can be divided into ordinal (categories that can be ordered) and nominal (categories which can not be ordered) data.
Numerical Data
Numerical data can be divided into discrete (obtained by counting) and continuous (obtained by measuring) data.
Population
In statistics, population refers to an entire group of people, objects, events, or measurements.
Census
A census is a survey of an entire population.
Sample
When the whole population is too big to survey, a representative sample is selected from the population to survey instead. The results are then used to make conclusions about the whole population.
Random Sample
A random sample is chosen in such a way that each member of the population has the same chance of being selected.
Systematic Sample
In a sytematic sample, the first item or person is selected randomly and all others are chosen at regular intervals.
Stratfied Sample
A random sample is chosen from each different strata (subgroups in the population eg gender or age) so that the proportion
of each strata in the sample matches their proportions in the population.
Bias
A sample is biased if it excludes the opinions of some part of the population which is being investigated.
Column Graph
A column graph (or bar chart) is used to display categorical or numercial data, It can display a large amount of data and show difference in the amounts in each category.
Line Graph
A line graph is used to show the changes in continuos numerical data over time. It can show a large amount of data and be used to estimate values between points. It can clearly show differnces and patterns in tha data.
Pareto Chart
A Pareto Chart contains a bar chart and a line graph combined. Individual values on the bar chart are shown in descending order. The cumulative total (as a percentage) is representd by the line graph.
Dot Plot
A dot plot is a simple type of column graph which allows small sets of data to be quickly displayed.
Stem-and-Leaf Plot
Sector Graph
A sector graph displays categorical data for a small number of categories. It easily compares the parts to the whole amount.
Divided Bar Graph
A divided bar graph displays categorical data for a small number of categories. It easily compares the parts to the whole amount.
Frequency Distribution Table
A frequency distribution table records the frequency of each score in a set of data.
Frequency Histogram & Polygon
A frequency histogram is a column graph that displays the data contained in a frequency distribution table.
