Unformatted text preview: Statistics: The Investigation Stage 1. Pose a Problem
ask a question identify the variables: independent variable (x-axis)
dependent variable (y-axis) Example: “Is there a relationship between the length and the wingspread of a bird?" 2. Hypothesis 3. Collect & Organize Data
Primary data: using a survey or an experiment to gather make an educated guess about the outcome / conclusion: “As the length of a bird increases, the wingspread increases” your own information
Secondary data: using someone elseﬂs data
Surveys are questionnaires given to a sample of the population A census is used when data is collected from every member
of the population
Charts, tables and frequency distribution tables are used to
organize data Lengths and Wingspreads of Birds LETS? 24 62 126 75 50 170 125 26 125 30
W'"(9:n':;e°d 27 75 150 170 100 250 300 50 350 100 4. Present Data
0 the type of graph used to display and interpret data
depends on the type of information and the purpose of the
investigation refer to the lesson Introduction to Statistics for the purpose of each type of graph: pictograph, broken line
graph, bar graph, histogram, circle graph, scatterplot a Line of Best Fit is used to show the relationship between
two variables in a scatterplot (positive correlation, negative correlation or no correlation) ScaTTerploT & Line of BesT HT 0 uses poinTs To show pairs of values 0 may help To show Trends 0 ofTen used To deTermine E a relationship exisTs beTween
Two variables 0 if 0 Trend exisTs, we can use a line of besT fiT or a curve
of besT fiT To besT represenT The daTa Example
LengThs and ngspreads of Birds
my“ 24 52 125 75 50 170 125 25 125 30
Wmﬂg‘g“ 27 75 150 170 100 250 300 50 350 100 use grid paper To ploT The daTa DeTermine The equaTion of your line of besT fiT
algebraically. Q (regain o
W 6W ; #x
6) W 7:7qu 5‘" Analysis of DaTa 1. CorrelaTion: Is There a relaTion?
Is There a posiTive or negaTive correlaTion? 2. CorrelaTion wiTh variables: Define The relaTion in words 3. Linear or Non—Linear?
Is The daTa besT represenTed by a sTraighT line or a curve? 4. Is (0, O) in The daTa? Is The dependenT variable zero when
The independenT variable is zero? 5. DiscreTe or ConTinuous
Does The daTa beTween The given seT have any meaning? - use grid paper To plot The data
— complete the same type of analysis for- arm span vs.
length of forearm Homework: pg. 63 Key Concep’rs
CZ pg. 64—65: #1, 3, 5 ...
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- Spring '11