Scatter Plots
Correlation
Lines of Best Fit
Interpreting Data
100

If the points on a scatter plot are widely spread and do not show any clear pattern, what does this indicate about the variables? 

  1. There is a strong positive correlation
  2. There is no correlation between the variables
  3. There is a strong negative correlation
  4. There is a perfect correlation

b. There is no correlation between the variables

100

The correlation coefficient for a perfect negative linear relationship.

-1

100

If the line of best fit for data is y = 2x + 3, what is the predicted y-value when x = 4?

11

100
Which is the stronger correlation?

-0.8 

0.8


Neither - they are equally strong.
200

When drawing a rectangle around the points of a scatter plot, what does it mean if the rectangle is vary narrow?

There is a strong correlation

200

If the correlation coefficient is 0.85, describe the strength and direction of the relationship.

strong positive correlation

200

Which of the following statements is true about a line of best fit? 

  1. It passes through every data point.
  2. It always starts at the origin.
  3. It minimizes the distance between itself and all the data points.
  4. It is always a horizontal line.

C. It minimizes the distance between itself and all the data points.

200

If a data set shows that as the number of absences increases, the final grade decreases, what is the correlation? 

  1. Positive correlation
  2. No correlation
  3. Negative correlation
  4. Zero correlation

C Negative Correlation

300

The term for a data point that does not fit the overall pattern of a scatter plot

outlier 

300

This is the range of possible values for the correlation coefficient, r.

-1 < r < 1
300

If a scatter plot shows a downward trend, what can you say about the slope of its line of best fit?

  1. The slope is negative.
  2. The slope is positive.
  3. The slope is zero.
  4. The slope is undefined.

 

a. The slope is negative.

300

What type of correlation does the situation describe:

The days Ms. Richardson says she prefers football and the Habs winning the hockey game.

No correlation.  
400

What is the main purpose of a scatter plot ?

To show the relationship between two variables.

400

Which of the following is the strongest correlation coefficient?


-0.95

0.05

0.5

0.3

-0.95

400

A line of best fit for a set of data is 

y = 3x + 1. 

What is the predicted value of y when x = 2?

7

400

Which statistic measures the strength and direction of a linear relationship between two variables? 

  1. Mean
  2. Range
  3. Correlation coefficient
  4. Mode

c. Correlation coefficient

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