Research methods - Correlations and Distributions

Question 1

Positive correlation

Answer 1

• means that as one variable rises, so does the other
  e.g. hours of study and average test score

Question 2

Negative correlation

Answer 2

• means that as one variable rises, the other one falls
  e.g. hours of TV watched each week and average test score

Question 3

Zero correlation

Answer 3

• if the correlation coefficient is 0, then the two variables aren’t linked
  e.g. students’ heights and average test score

Question 4

Correlation research: advantages

Answer 4

• couldn’t do a controlled experiment
• can give ideas for future research
• can be used to test reliability and validity

Question 5

Correlation research: disadvantages

Answer 5

• can’t establish ‘cause and effect’ relationships
• care must be taken when interpreting correlation coefficients

Question 6

The Normal Curve

Answer 6

1. The curve is symmetrical - shaped like a bell with its peak at the mean
2. A different mean shifts the centre of the bell horizontally
3. The width of the curve depends on the standard deviation

Question 7

Positive Skew

Answer 7

• cluster of scores at the lower end of the data set
• curve has a tail on the right side of the peak: it is said to her skewed to the right
• the mode is less than the median, which is less than the mean

Question 8

Negative Skew

Answer 8

• more scores as the higher end of the data set
• tail is on the left side of the peak: it is skewed to the left
• mode is more than the median, which is more than the mean