1.
What does a scatter plot show?
Correct Answer
B. Relationship between two variables
Explanation
A scatter plot shows the relationship between two variables by plotting data points on an x and y-axis. Each point represents the values of the two variables for a single data entry. By analyzing the pattern or trend of the points, we can determine whether a relationship exists between the variables, and if so, whether it is positive, negative, or absent. Scatter plots are widely used in statistics because they visually represent correlations, making it easier to spot trends, outliers, or clusters in the data. This tool is especially useful in exploring and explaining relationships in quantitative data.
2.
What type of correlation does an upward trend in a scatter plot indicate?
Correct Answer
A. Positive correlation
Explanation
An upward trend in a scatter plot indicates a positive correlation. This means that as one variable increases, the other variable also increases. For example, as the number of hours studied increases, the test score might also rise, reflecting a direct relationship between the two. In positive correlations, the data points tend to slope upward from the bottom left to the top right of the graph. The strength of the correlation depends on how closely the data points follow the upward trend, with stronger correlations appearing as tighter clusters along a straight line.
3.
If points in a scatter plot are randomly scattered, what is the likely correlation?
Correct Answer
C. No correlation
Explanation
If the points in a scatter plot are randomly scattered without any discernible pattern or trend, the likely correlation is no correlation. This means there is no significant relationship between the two variables being measured. Changes in one variable do not predict or correspond with changes in the other variable. This randomness suggests that the variables operate independently of each other. For instance, shoe size and intelligence have no meaningful relationship, so a scatter plot representing these variables would show no correlation, with data points scattered in all directions.
4.
What does it mean if data points in a scatter plot form a straight line?
Correct Answer
C. Perfect correlation
Explanation
When data points in a scatter plot form a straight line, it indicates a perfect correlation. In this case, the relationship between the two variables is so consistent that every increase in one variable corresponds exactly with an increase (positive correlation) or decrease (negative correlation) in the other variable. In real-world scenarios, perfect correlations are rare, but they might be seen in theoretical data or very controlled environments. The straight line reflects complete predictability between the two variables, meaning you can accurately estimate one variable based on the value of the other.
5.
In a scatter plot, if one variable increases while the other decreases, what correlation is shown?
Correct Answer
C. Negative correlation
Explanation
A scatter plot showing that one variable increases while the other decreases reflects a negative correlation. In this inverse relationship, as one variable grows, the other shrinks. For example, as the speed of a car increases, the time to reach a destination decreases. In the scatter plot, the data points would slope downward from the top left to the bottom right. The strength of the negative correlation depends on how closely the points follow this downward slope. Stronger negative correlations appear as tighter clusters of points along the line.
6.
What is the strength of correlation when points are close to a straight line?
Correct Answer
A. Strong correlation
Explanation
When data points in a scatter plot are clustered closely along a straight line, this reflects a strong correlation, indicating that changes in one variable reliably predict changes in the other. A strong correlation can be positive or negative but shows consistency in the relationship between the two variables. The closer the data points are to the line, the more predictable the relationship, meaning that one variable can be used to make accurate predictions about the other. This makes strong correlations valuable in research and analysis for drawing meaningful conclusions from data.
7.
Which tool is used to measure the strength of a correlation in a scatter plot?
Correct Answer
A. Line of best fit
Explanation
The line of best fit is used to measure the strength of a correlation in a scatter plot. This line is drawn to minimize the distance between the points and the line itself, providing the best estimate of the overall trend in the data. The closer the data points are to this line, the stronger the correlation. A line of best fit helps in identifying whether the relationship between the variables is positive, negative, or absent. It also quantifies the degree of correlation, making it easier to interpret the scatter plot.
8.
What does a downward trend in a scatter plot represent?
Correct Answer
B. Negative correlation
Explanation
A downward trend in a scatter plot represents a negative correlation, meaning that as one variable increases, the other variable decreases. For instance, as the price of a product increases, demand for it may decrease. In such a plot, the data points form a slope descending from the top left to the bottom right of the graph. The tighter the points are to this downward slope, the stronger the negative correlation. A clear downward trend visually conveys an inverse relationship, making it easy to understand how the variables are connected.
9.
What does it mean if points in a scatter plot are widely spread out?
Correct Answer
B. Weak correlation
Explanation
If the points in a scatter plot are widely spread out, it suggests a weak correlation. While there may be some trend or pattern, the data points are not closely clustered along a line, indicating that the relationship between the two variables is weak and inconsistent. This means that changes in one variable only loosely predict changes in the other. Weak correlations make it harder to draw reliable conclusions from the data. In these cases, other factors may be influencing the variables, and the relationship between them is less predictable.
10.
What does a correlation value of zero mean in a scatter plot?
Correct Answer
B. No correlation
Explanation
A correlation value of zero in a scatter plot means there is no correlation between the two variables. This indicates that changes in one variable do not affect the other in any consistent way. In the scatter plot, the data points would appear randomly distributed, with no discernible upward or downward trend. A zero correlation suggests that the variables are independent of each other, and there is no linear relationship present. This lack of correlation can be significant in research, as it highlights variables that do not have a predictive connection.