Measures of Central Tendency
What is the mode?
The mode is the value that appears most frequently in a dataset.
What is the main difference between qualitative and quantitative data?
Qualitative data describes qualities or characteristics, while quantitative data involves numerical values that measure quantity.
What does a correlation coefficient measure?
A correlation coefficient measures the strength and direction of a relationship between two variables.
What does a t-test compare?
A t-test compares the means of two groups.
What is a hypothesis in psychological research?
A hypothesis is a testable prediction about the relationship between variables in a study.
How is the median calculated?
Write an example
The median is found by ordering the data and selecting the middle value.
Name two examples of nominal data.
Examples include gender (male/female) and eye color (blue/brown).
What does a correlation coefficient of 0 indicate?
A correlation coefficient of 0 indicates no relationship between the variables.
When would you use a Mann-Whitney U (MWU) test instead of a t-test?
The MWU test is used instead of a t-test when data is not normally distributed.
Define a null hypothesis.
A null hypothesis states that there is no effect or difference between variables.
Which measure of central tendency is most affected by extreme values?
The mean is most affected by extreme values (outliers).
Identify whether “height in centimeters” is continuous or discrete data.
Height in centimeters is continuous data.
Which correlation coefficient is best for data that is not normally distributed?
Spearman’s correlation coefficient is best for non-normally distributed data.
What assumption about the data is required to perform a parametric test?
Parametric tests require data that is normally distributed.
When an alternative hypothesis is supported, what does it suggest about the null hypothesis?
If the alternative hypothesis is supported, it suggests that the null hypothesis should be rejected.
If a dataset has two modes, what is it called?
A dataset with two modes is called bimodal.
Describe ordinal data and provide an example.
Ordinal data represents categories with a meaningful order but no consistent interval, such as rankings in a race (1st, 2nd, 3rd).
What is the difference between Pearson’s and Spearman’s correlation?
Pearson’s correlation measures linear relationships in continuous, normally distributed data; Spearman’s measures monotonic relationships and can handle ordinal data.
Explain when to use an independent t-test (unmatched) versus a paired (matched) t-test.
An independent t-test compares two different groups, while a paired t-test compares two measurements from the same group.
Why is it important for a hypothesis to be testable?
A testable hypothesis can be scientifically examined and verified through evidence.
Given the data set {3, 5, 7, 10, 12}, calculate the mean, median, and mode.
Mean: (3+5+7+10+12) / 5 = 7.4; Median: 7; Mode: There is no mode.
Explain how interval data differs from ratio data, including an example of each.
Interval data has equal intervals between values but no true zero (e.g., temperature in Celsius). Ratio data has equal intervals and a true zero (e.g., weight in kilograms).
Describe how a strong positive correlation would be represented on a scatter plot.
A strong positive correlation would show points close together in an upward-sloping line.
Describe a scenario in which a researcher would use a non-parametric test, and explain why.
A non-parametric test might be used if data is ordinal or not normally distributed, such as comparing ranks instead of means.
The effectiveness of advertising for two rival products (Brand X and Brand Y) was compared. Market research at a local shopping centre was carried out, with the participants being shown adverts for two rival brands of coffee, which they then rated on the overall likelihood of them buying the product (out of 10, with 10 being "definitely going to buy the product"). Half of the participants gave ratings for one of the products, the other half gave ratings for the other product.
Create an example of both a null hypothesis and an alternative hypothesis for an experiment on the effects of sleep on memory.
Null hypothesis: “Sleep has no effect on memory recall.” Alternative hypothesis: “Sleep improves memory recall.”