Deck 8: Correlation

Question 1

Which of the following statements would you consider to be a good example of negative correlation?

A) The rate of uptake of measles vaccination increasing with a corresponding increase in reported incidence of measles cases
B) The rate of measles incidence increasing with a decreasing uptake of measles vaccination
C) The incidence of measles illness decreasing with the rising numbers of measles immunization uptake
D) None of the above

Answer 1

The incidence of measles illness decreasing with the rising numbers of measles immunization uptake

Question 2

A scatterplot shows

A) The frequency with which values appear in the data.
B) The average value of groups of data.
C) Scores on one variable plotted against scores on a second variable.
D) The proportion of data falling into different categories.

Answer 2

Scores on one variable plotted against scores on a second variable.

Question 3

What is meant by a 'spurious' relationship between two variables?

A) One that is so illogical it cannot possibly be true
B) An apparent relationship that is so curious it demands further attention
C) A relationship that appears to be true because each variable is related to a third one
D) One that produces a perfect negative correlation on a scatter diagram

Answer 3

A relationship that appears to be true because each variable is related to a third one

Question 4

Twenty people took part in study in which they completed two questionnaires: one that measured musical ability and one that measured their mathematical aptitude. The two sets of scores were then analysed to determine if the two skills were related. Which research design was used in the study?

A) An observational study
B) A case study
C) A correlational study
D) An experiment

Question 5

In order for accurate measures of the linear relationship between two variables to be achieved, what type of data are required if using Pearson's correlation coefficient?

A) Interval
B) Ratio
C) Ordinal
D) Categorical

Question 6

What is the name of the test that is used to assess the relationship between two ordinal variables?

A) Spearman's rho
B) Phi
C) Cramér's V
D) Chi-square

Question 7

When interpreting a correlation coefficient, it is important to look at:

A) The significance of the correlation coefficient.
B) The magnitude of the correlation coefficient.
C) The sign of the correlation coefficient.
D) All of the above.

Question 8

How much variance has been explained by a correlation of .9?

A) 81%
B) 18%
C) 9%
D) None of the above

Question 9

A positive correlation shows that

A) Two variables are unrelated.
B) As one score increases, so does the other.
C) As one score increases, the other decreases.
D) Both a and

Question 10

The relationship between two variables, controlling for the effect that a third variable has on one of those variables, can be expressed using a

A) Semi-partial correlation.
B) Bivariate correlation.
C) Point-biserial correlation.
D) Partial correlation.

Question 11

A researcher conducts some research in which they identify a significant positive correlation (r = .42) between the number of children a person has and their life satisfaction. Which of the following is it inappropriate to conclude from this research?

A) That having children makes people more satisfied with their life.
B) That someone who has children is likely to be happier than someone who doesn't.
C) That the consequences of having children are unclear.
D) That it is possible to predict someone's life happiness partly on the basis of the number of children they have.

Question 12

A researcher is wishing to undertake a study of the relationship between a specific type of analgesia and levels of pain experienced by sufferers of rheumatoid arthritis. It is believed that level of physical activity will influence both of these variables and so it has been decided that the use of partial correlations will allow for this in the research. On which of the following should a correlation be performed?

A) Type of analgesia used and level of pain experienced, controlling for level of physical activity
B) Level of pain experienced and level of physical activity, controlling for type of analgesia used
C) Type of analgesia used and physical activity level, controlling for level of pain experienced
D) None of the above

Question 13

One of the factors that affect the reliability of findings from studies using correlations is

A) The number of variables being investigated.
B) The type of relationship that is found.
C) The level of significance set at the start of the study.
D) The number of people who take part.

Question 14

The correlation between two variables A and B is .12 with a significance of p < .01. What can we conclude?

A) That there is a substantial relationship between A and B
B) That there is a small relationship between A and B
C) That variable A causes variable B
D) All of the above.

Question 15

Correlational studies allow the researcher to

A) Test for differences between two variables.
B) Predict the effect of one variable upon another.
C) Make causal inferences about the relationship between two variables.
D) Identify the relationship between two variables.

Question 16

If there were a perfect positive correlation between two interval/ratio variables, Pearson's r test would give a correlation coefficient of

A) -.33.
B) +1.
C) +.88.
D) -1.

Question 17

The covariance is

A) An unstandardized version of the correlation coefficient.
B) A measure of the strength of relationship between two variables.
C) Dependent on the units of measurement of the variables.
D) All of the above.

Question 18

A study undertaken to determine whether sugar-free drinks reduced tooth decay in adolescents gave a probability of .0015 associated with the correlation coefficient. What can be deduced about this result?

A) The hypothesis is true.
B) The result is not significant.
C) There is a 0.15% that the result is due to sampling error and so the null hypothesis is true.
D) There is a 0.15% chance that the result is correct.

Question 19

Which of the following statement about Pearson's correlation coefficient is not true?

A) It can be used as an effect size measure.
B) It varies between -1 and +1.
C) It cannot be used with binary variables (those taking on a value of 0 or 1).
D) It can be used on ranked data.

Question 20

Which of the following techniques is a good way of assessing whether two variables are related to each other?

A) Calculating variance
B) Calculating covariance
C) Calculating correlation
D) Calculating standard deviation

Question 21

Which of the following is not an example of a test used to correlate non-parametric data?

A) Spearman's correlation
B) Pearson's correlation
C) Kendall's correlation
D) None of the above

Question 22

Under what conditions would Spearman's correlation coefficient be used?

A) When data are distributed normally.
B) When data are non-normally distributed.
C) When data are distributed parametrically.
D) None of the above.

Question 23

A study undertaken in a surgical ward determined that the use of a specific antibacterial handwash was considered to be the most effective and cost effective. Which of the following results would be considered most significant?

A) p < .01
B) p < .001
C) p < .0005
D) p < .0001