Data Processing, Presentation and Interpretation Key Terms
Variable: A value that varies
Random variable: A value that varies randomly
Frequency: The number of times a value occurs in a data set
Categorical data: Data in categories (also known as qualitative data)
Numerical data: Data defined in some way by numbers
Ranked data: Ordered data - Data given by their position in a group rather than by
measurements or scores
- Median: Value in the middle of the data set (for n times, median = (n+1)/2 th item).
Resistant to outliers
- Lower quartile: Value in the middle of the start and middle values
- Upper quartile: Value in the middle of middle and end values
- Interquartile range: Difference between upper and lower quartile
- Range: difference between highest and lowest value
- Semi interquartile range: Half the interquartile range
- Box plot and cumulative frequency: Used to display ranked data
Discrete variables: They can take certain particular values but not those in between
Continuous variables: They can take any particular value. You cannot list all the possible
values
Distribution: The pattern in which data is displayed or occurs
Unimodal: If there is one peak in the distribution
Bimodal: When there are two peaks in the distribution
Positive skew: When the distribution is skewed to the left (smaller values of ‘x’)
Negative skew: When the distribution is skewed to the right (larger values or ‘x’)
Grouped data: When there are many possible values for a variable, it is convenient to
allocate the data to groups
- Grouped frequency table: When individual values are not known and instead of
discrete values for the variable, there is a group the value can be put in (I.e. 0-9,
10-19, 20-29, etc for ages)
Ungrouped data: Data that is first gathered from experiments or studies, the data is raw, not
categorised, classified or otherwise sorted or grouped.
Bivariate data: When there are two variables attached to each item
Multivariate data: When there are more than two variables attached to each item
Ways of presenting categorical data: pictograms, bar charts, dot plots and pie charts
Modal class: The class with the highest frequency
Central tendency:
1. Mode: The value that occurs most commonly in a data set
2. Median: Covered above
3. Mean:
- Arithmetic: Found by adding the individual values together and dividing by
the number of values added
- Weighted mean: When the sum of the frequencies multiplied by the value of
the variable is divided by the sum of the frequencies (sigma fx / sigma f)
4. Mid range: The mean of the maximum and minimum value
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller ALevelUp. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $3.90. You're not tied to anything after your purchase.
