Summary
Summary Descriptive Statistics Notes
- Course
- Institution
A summary of the notes in a concise and easy to read manner
[Show more]
Seller
Follow
maryonanna
Content preview
Descriptive statisticsDiscrete or continuous data?
1) Categorical
Has two or more categories with no ordering to them e.g. hair colour, job title
2) Discrete (usually ordinal, ratio or interval variables)
Has a fixed value with a logical order e.g. shoe size, score out of 10
3) Continuous (usually ratio or interval variables)
Can take any fractional value e.g. reaction times
Frequency distributions
Categorical data – can be presented as its raw frequency or as a percentage frequency e.g. what's
your least favourite a level subject? Shown in a bar chart of the number / percentage of students
according to each subject
Discrete data – can be presented as a cumulative frequency or percentage e.g. how did students
score on a test? If there are lots of values use frequency ranges to present this instead e.g. score 1-
2 , 3-4 etc
Measures of central tendency
Sometimes we want to condense the entire frequency distribution to a single
number
This is where we might calculate the central tendency of the data
Mode – the most frequently occurring score in a dataset
Median- the middle score in a dataset
Mean – sum of data points/ number of data points
Mode
- Most common score
- Can be used for nominal data
- Sometimes takes more than one value (bimodal and multimodal distributions)
Median
- The middle value in a dataset, or the mean of the middle two values
- E.g. in this data there are 89 participants
- Median value = value number 45 – 45 th value = 8
- Pros – insensitive to outliers, often gives a real / meaningful data value, useful for ordinal
data and skewed interval/ratio data
- Cons – ignores a lot of the data, difficult to calculate without a computer, can’t use this with
nominal data
Mean
- Sum of values divided by number of data points
- E.g. sum of data points =600, number of data points = 89 – 600/89= 6.74
- Students scored on average a 6.74 out of 10 on this test
- Pros – uses all of the data, is most effective for normally distributed datasets
- Cons – sensitive to outliers, values are not always meaningful (we can’t get a score of 6.74
out of 10), only meaningful for ratio and interval data
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 maryonanna. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $6.43. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
71184 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now