Correlation Practice Quiz Flashcards
(47 cards)
Which statement is true about Spearman correlation?
a) It is sensitive to outliers
b) It requires normally distributed data
c) It is based on ranked data
d) It measures only positive associations
C
A research is examining the relationship between academic test scores and workplace efficiency for 40 participants. How many degrees of freedom should be considered to assess whether the correlation is statistically significant?
a) 40
b) 36
c) 39
d) 38
D
A study revealed a significant correlation between the number of people who reported improved sleep quality and coffee consumption. Friend advises to drink coffee to sleep better. Which common misunderstanding about correlation is this?
a) Homogeneity of sample variance
b) Restriction of range
c) Correlation implying causation
d) Unreliable measures
C
A researcher is studying the relationship between 2 variables: daily exercise time and stress levels. Based on the statistical concept of correlation, what is the possible range of the correlation coefficient?
a) -1 to 1
b) 0 to 1
c) -1 to 0
d) None
A
A psychologist is analysing the relationship between stress levels and hours of sleep in a large sample of individuals.
Which of the following values is impossible for a correlation coefficient?
a) -1.0
b) 1.0
c) 1.08
d) -0.34
C
Correlation coefficient (r) found to be -0.5 and the 95% confidence interval is calculated to range from -0.6 to -0.4. Which of following statements
a) There is a 95% chance that the true population correlation lies between -0.6 and -0.4
b) Population correlation must be exactly -0.5
c) This confidence interval suggests there is no relationship between screen time and sleep quality in the population
d) If the study was repeated, sample correlation would always be between -0.6 and -0.4
A
To establish a correlation between hours spend studying and exam performance, which of the following conditions must be met?
a) Measures of hours spent studying and exam performance from each student in a single group
b) Measures of hours spent studying from one group of students and exam performance from another group
c) 2 seperate groups of students- 1 measured for hours spent studying and the other for exam performance
d) Group of students where half are measured for hours spent studying and the other half for exam performance
A
Researcher finds following correlations between variables:
- Daily caffeine intake and stress levels- r= -0.91
- Screen time and sleep quality- r= -0.92
Researcher concludes that increased caffeine intake strongly reduces stress as the correlation is close to -1. Which of the following statements is the most accurate about the researchers conclusion?
a) Researcher is correct as a correlation coefficient of -0.91 indicates a very strong relationship where higher caffeine intake directly reduces stress
b) Researcher is incorrect because a negative correlation doesnt imply causation. Strong correlation only suggests that as caffeine intake increases, stress levels tend to decrease, other factors may be involved
c) Researcher incorrect as correlations closer to -1 are weaker than positive correlations closer to 1
d) The researcher is correct, but the strongest relationship in the data is screen time and sleep quality, so caffeine intake is less important
B
A researcher is analysing two variables believed to be completely independent of eachother. Which of the following values would most likely represent the correlation between the 2 variables?
a) 1
b) 0
c) -1
d) Need more info so cannot determine
B
What happens to the standard Spearman formula when ties occur?
a) It remains completely accurate
b) It becomes slightly inaccurate
c) It cannot be used at all
d) It becomes more accurate
B
Researcher collects data on students study hours per week and their final exam scores. Ranks of the 2 variables are calculated, researcher finds the sum of squared differences between paired ranks (∑ d²) to be 10 with a sample size of 5 students.
What is the Spearman correlation coefficient (rₛ) ?
a) 0.90
b) 0.70
c) 0.50
d) 0.30
C
After ranking both variables, sum of squared differences (∑ d²) is found to be 0.
Based on the Spearman rank correlation formula, what does this indicate about the relationship between sleep duration and reaction time?
a) There is no correlation between sleep and reaction time
b) The two variables are perfectly correlated
c) The correlation is weak but still positive
d) The correlation is negative but not strong
B
What is the key difference between independent and dependent correlations?
a) Independent correlations come from the same sample, while dependent correlations come from different samples
b) Independent correlations involve correlations between unrelated variables, dependent correlations involve correlations that share a common variable
c) Dependent correlations refer to correlations between categorical variables, while independent correlations refer to numerical variables
d) Independent correlations are always stronger than dependent correlations
B
A company finds a covariance of -25 between employee job satisfaction and working hours. What is the bets interpretation of this result?
a) Employees with higher job satisfaction tend to work fewer hours
b) There is no relationship between job satisfaction and working hours
c) Employees who work more hours are always dissatisfied
d) Job satisfaction causes a decrease in working hours
A
Which of the following is NOT an assumption of Pearson correlation?
a) The relationship between the variables must be linear
b) The variables must be measured on an ordinal scale
c) Both variables must be continuous or at least interval-level data
d) There should be no significant outliers that distort the relationship
B
Researcher examining correlation between 2 variables. Find that the scatterplot shows a clear curvilinear relationship. What should they do next?
a) Apply Pearson correlation since it can handle all types of relationships
b) Use a different statistical test such as Spearman correlation
c) Ignore the shape of the relationship because correlation only measures strength
d) Convert the variables to ordinal scales and run Pearson correlation
B
A psychologist measures the correlation between daily caffeine consumption (mg) and productivity scores and finds: r = 0.12, p = 0.48
What is the best interpretation of this result?
a) Caffeine consumption has a strong positive effect on productivity
b) There is no statistically significant relationship between caffeine consumption and productivity
c) Since p> 0.05, there is no correlation at all
d) The correlation is negative, meaning more caffeine decreases productivity
B
When converting data to ranks for Spearman correlation, what is the most appropriate method for handling ties?
a) Assigning each tied value the average of the ranks they would occupy, to preserve the overall distribution of ranks
b) Breaking ties randomly, to avoid bias in the ranking process
c) Assigning a rank of zero to all tied values, as they do not contribute to the analysis
d) Excluding tied values from the analysis, to ensure the dataset consists only of unique ranks
A
If time spent exercising and daily water consumption are highly correlated in individuals, what does that tell us?
a) People who spend more time exercising also tend to drink more water
b) High amounts of exercise lead directly to higher water consumption
c) Exercise and water consumption always occur together
d) Nothing else could explain the relationship between exercise and water consumption
A
What does a correlation of +1.00 indicate?
a) A weak positive relationship between 2 variables
b) A perfect positive linear relationship between 2 variables
c) A weak negative relationship between 2 variables
d) No relationship between 2 variables
B
If you see a scatterplot where the points are tightly clustered around an upward-sloping line, what does this mean?
a) Theres no relationship between the variables
b) The variables are negatively correlated
c) The variables have a strong positive correlation
d) The correlation is weak and unreliable
C
Imagine you are given the following values:
- Covariance cov (x,y)= 50.3
- SD Sx= 5.1
- SD Sy = 10.8
What is the correlation coefficient r(x,y)?
a) 0.91
b) 0.72
c) 0.88
d) 0.49
A
Which of the following best explains why correlation doesnt imply causation?
a) Correlation is a causal method
b) A third variable might be involved
c) Correlation uses experimental designs
d) Correlation always implies direction
B
What does correlational research primarily investigate?
a) Cause and effect between variables
b) Whether 2 variables are related
c) The manipulation of variables
d) Random assignment of participants
B
