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POPULATION
• The set of all things or people being studied• A group of people you want information about• Examples– All the students of Fairwind– All the students of 806 and 808– All the salmon in Lake Ontario– All Canadians
CENSUS
• A method to collect data where ALL people in the population are surveyed
• Governments conduct censuses to ensure they get information about ALL citizens
• If you were to ask all classmates about their favourite movie, it would be a census
SAMPLE
• A PART of a population that is studied or surveyed
• Provides information about the entire population
• Should be representative (have qualities of the whole population) in order to have valid results
SURVEY
• A method of collecting data where people are asked questions
• Usually only asked to a sample of a population• A valid survey is one where the results are
good because the sample chosen and the method of asking questions are UNBIASED
BIAS
• UNFAIR• When a question is worded such that a
particular answer is favoured• When a surveying method is chosen that
unfairly represents the population• Leads to INVALID results
UNBIASED
• FAIR• Leads to VALID results• Proper sampling methods were used• Proper questions were used
TREND• A pattern or sequence• Trend up (generally heading up)• Trend down (generally heading lower)• Trend can be even (staying the same)• EX:– Climate change is an upward trend in average
temperature– The use of CDs is on a downward trend
INTERVAL
• Continuous data should be sorted into intervals in order to be shown on a histogram
• Ages of a population can be grouped by 10s– 0-9– 10-19– 20-29– 30-39
SCALE
• The numbers on the axes of a graph• Should count up by the same
amount each time (by 2s, 3s, or 10s, for example)
MEAN
MEDIAN
MODE
CATEGORICAL DATA
• Data that can be arranged into categories• Colours• Gender (male or female)• Types of something (flavours, fruit, sports…)• Favourite ‘something’ (movie, song, artist…)• Bar graphs are ideal
DISCRETE DATA• Data that can only be specific values • Data is counted• Class sizes can only be whole numbers (you can’t
have 22.5 students)• Shoe sizes - only whole and half sizes• Number of phone calls• Number of children in a family• Number of languages one speaks• Bar graphs are ideal• Scatterplots can compare two types of discrete sets
CONTINUOUS DATA
• Data can have any value• Often measurements of:– Height, Length, Width– Ages– Times– Temperatures
• Histograms are ideal
PRIMARY DATA
• Data collected by yourself• You have collected the data through:–Recording observations–Recording experiment data–Surveys you created–A census you created
SECONDARY DATA
• Data or information NOT collected by you• Data collected by others• Includes data from–Published books– Internet–Published graphs and charts provided by
your teacher
• Justify: prove it!• Interpret: What do you see? What does the
data mean?• Conclude (make conclusions): What are facts
from the data?• Outlier: one piece of data that is MUCH
greater or MUCH less than all others
SCATTERPLOTS
HISTOGRAMS
FREQUENCY TABLES
BAR GRAPH
CIRCLE GRAPH
LINE GRAPH
• Good for showing change over time