Unit 3 Review

• Data:– A variable is an attribute that can be measured– One Variable Data: measures only 1 attribute for

each data point.– Two Variable Data: measures 2 attributes for each

data point.

One Variable Data Two Variable Data

- Tally Charts- Frequency Tables- Bar Graphs- Histograms- Circle Graphs- Pictographs

- Ordered Pairs- Scatter Plots- Two –Column Tables of Values

• Graphs:

– Know how to draw a graph.– Always include a TITLE– Dependent Variable goes on the y-axis– Independent Variable goes on the x-axis– Label the dependent and independent variables– Label the x and y axes (with an x and a y!)

• Correlation:– Is a relationship between 2 variables

• Positive Correlation:– Both variables increase together– Points on the graph go “up and to the right”

• Negative Correlation:– One variable increases while the other variable

decreases.– Points on the graph go “down and to the right”

• Correlation:Positive Correlation Negative Correlation

• Correlation:– A correlation DOES NOT indicate a Cause-and-

Effect Relationship.• It indicates that there MIGHT be a cause-and-effect

relationship.

– Weak Correlation – Points are spread out– Strong Correlation – Points are packed tightly

together along a line.– No Correlation – Points are just all over the place.

No real trend.

• Line of Best Fit:– Also called:• Regression Line• Trend Line

– Must fit the data trend and should have as many points on the line as possible.

– If all points cannot be on the line then there should be as many points on the line as possible AND the same number of points above the line as there are below the line

– To determine the Equation of the Line of Best Fit:

• Find the slope (m)

• Find the y-intercept (b)– This can be done by finding where the line of best fit crosses

the y-axis using the graph OR– Algebraically – This is the BEST option

• Write the final equation in the form y = mx + b

• Determine an equation for the line of best fit• Use the equation to predict the average of a

student who does 25 minutes of homework.• Use the equation to predict the amount of

homework done by a student who is earning 95%

• Predictions:– Predictions can be made by using the Line of Best

Fit.

– Interpolation:• Prediction of data points BETWEEN KNOWN points.

– Extrapolation:• Prediction of data points OUTSIDE KNOWN points.

• Predictions:– When using a graph to Interpolate or Extrapolate

make sure to:• Draw in the dotted line from the given axis up (or over)

to the line of best fit and then over (or down) to the other axis. (SHOW YOUR WORK!!)

– Eg.

• Reliability of a Linear Model:

– What can reduce the reliability of a Linear Model?• A WEAK linear correlation• A non-linear correlation• Data that are too clustered• Outliers in the data• A data sample that is too SMALL• A data sample that is BIASED

• These Notes are a STARTING POINT.• You need to add things that YOU want in YOUR

note.• This is just how I would organize things and

how my brain works. Yours might be different, so adjust the information so it fits what you need.

• You should be MEMORIZING the information in the notes (don’t necessarily memorize the examples unless you want to)

• Once you can re-write your notes after you’ve taken a few hour break, without looking at the originals and from reading them, then

• Do as many practice questions as you can find.

• If you need more questions, see me and I’ll provide more.

• Use your textbook for info, examples, and practice questions.

• Textbook:– Every section of the textbook has practice

questions associated with it.– Every Chapter has a:• Mid-Chapter Review Section halfway thru the chapter• Chapter Summary at the end of the chapter.• Chapter Review questions at the end of the chapter• Chapter Practice Test

– It’s an almost endless supply of questions…….Use them!

– Re-do your old tests too to test yourself.