LECTURE 4 Flashcards
What is a stem-and-leaf plot?
A way to display data where the “stem” represents the tens and the “leaf” represents the units
What information can a boxplot show?
Median, range, interquartile range (IQR), and skewness of a dataset.
What does the range of a dataset measure?
The difference between the highest and lowest values.
What is the interquartile range (IQR)?
The range of the middle 50% of a dataset, from Q1 (25th percentile) to Q3 (75th percentile).
What is skewness in data?
A measure of symmetry in a distribution.
What is positive skew?
When data is skewed with a long tail on the right (high values).
What is negative skew?
When data is skewed with a long tail on the left (low values)
What does kurtosis measure?
The “tailedness” or sharpness of the peak in a distribution.
What is mesokurtic kurtosis?
A normal distribution with kurtosis = 3.
What is leptokurtic kurtosis?
A distribution with a sharp peak and heavy tails (kurtosis > 3).
What is platykurtic kurtosis?
A distribution with a flat peak and light tails (kurtosis < 3).
How does skewness statistic determine normality?
Skewness values within -1 to 1 indicate a normal distribution.
What is the purpose of histograms in statistics?
To show the frequency distribution of data.
What is a probability distribution?
A smooth curve showing the likelihood of values in a dataset.
What is a normal distribution?
A symmetric, bell-shaped curve centered around the mean.
Why is normality important in statistics?
Many statistical tests assume data is normally distributed for accurate results.
What are error bars?
Visual indicators of variability in data, often representing 95% confidence intervals.
What do overlapping error bars indicate?
No significant difference between conditions.
What do non-overlapping error bars indicate?
A significant difference between conditions.
What is a scatterplot used for?
To illustrate correlations between two variables.
What does a line of best fit represent in a scatterplot?
The trend or relationship between the variables.
What are some common mistakes in figures?
Missing titles, unclear labels, inconsistent scales, and misleading representations.
How can figures be misleading?
By manipulating axes, omitting scales, or using unclear legends.
What is an example of a misleading figure?
Hiding differences by using inappropriate y-axis scales.
hat is the purpose of a bar chart?
To compare different groups or conditions visually.
Why should error bars be added to bar charts?
To show variability and confidence intervals, making interpretations more reliable.
What should be avoided in figures?
Inconsistent formatting, ambiguous labels, and lack of context.
What is the role of visual aids in reports?
To summarize data, show trends, and make results easier to understand.
Where should visual aids for assessing data go in a report?
In the appendix.
Where should visual aids for presenting results go in a report?
In the results section.
What is kurtosis’s practical importance?
It indicates the likelihood of outliers, which affects the interpretation of data.
How do you determine skewness in R?
Using skewness statistics, histograms with normality curves, or probability density curves.
