Correlations workshop activity Flashcards
True or false
+0.8 is stronger than –0.8.
False (number = strength)
True or false
0.5 is twice as strong as 0.2
False, No. Separate correlations cannot be directly compared in this way.
True or false
The values of both variables decrease in a negative coefficient
False
True or false
The values of both variables increase in a positive coefficient.
True
True or false
A zero coefficient would indicate that data points are closely packed
around a horizontal trend line.
False, they would be randomly everywhere
A Pearson test can be used with ordinal data. True or false
False (see exam reference material)
A Spearman test cannot be performed on ratio data. True or false
False (see exam reference material)
The relationship between driver age and number of car accidents is
described as having a correlation coefficient of -0.8. What does this mean?
The relationship is a strong one (because the number is close to 1) and it is
an inverse relationship (because of the negative sign).
In practice this means that as driver age increases there will be fewer
accidents.
The relationship between driver age and reaction times demonstrated in simulated driving tests is described as having a correlation coefficient of
0.4. What does this mean?
The relationship is a moderate one and it is a direct relationship (as one
variable increases so does the other).
In practice this means that as driver age increases there will be a
moderate increase in reaction times.
Would it be useful to comment that the correlation between driver age and number of car accidents is twice as strong as the correlation between driver age and reaction times?
No. Separate correlations cannot be directly compared in this way.
There may be some link between age, number of accidents and reaction times but a correlation test that looked at the three way relationship would have to be used.
