Exam (elaborations)
Lecture and Lab Set on Descriptive Statistics questions n answers
- Course
- Institution
Lecture and Lab Set on Descriptive Statistics questions n answers
[Show more]
Content preview
Lecture and Lab Set on DescriptiveStatistics
What is descriptive statistics, broadly speaking? Why would we want to use descriptive statistics? -
correct answer ✔✔- With descriptive statistics, we have a numerical or quantitative summary of the
characteristics of a data set.
- We want to work with descriptive statistics because a simple summary is more efficient and effective
than a large set of values.
What are the two main ways we want to summarize data? Describe them. - correct answer ✔✔-
Measures of central tendency: the center of a data distribution given a group of data.
- Measures of dispersion: measure the spread of a data distribution given a list of data
These both are forms of summary. They help us BETTER UNDERSTAND our data from a broad point of
view.
What is a mode? Describe multimodal, bimodal, etc. - correct answer ✔✔Given a list of data, for any
value, if the value occurs most frequently, the value is the mode.
>>> Bimodal: two peaks
>>> Multimodal: multiple peaks
We don't always have a mode!
What is the median? How do we go about determining the median? - correct answer ✔✔The median is
the middle value from a set of ordered values - it is the VALUE with an EQUAL NUMBER of data above
and below it.
How do we determine the median?
, 1. Order data from smallest to largest FIRST.
2. If the number of values (n) is odd, median is the middle number in the list of ordered values.
Essentially, it should be at position (n+1)/2.
3. BUT, if the number of values (n) is even, then our median is the average of the middle two values.
What is the mean? What is the difference between the sample and population means? - correct answer
✔✔- The mean itself is the sum of the values divided by the number of values.
- The sample mean is the mean of observations. It is X BAR.
- Population mean is MU.
What is weighted mean? What does "weight" mean here? - correct answer ✔✔A weighted mean is a
meal where there is some variation in the relational contribution of individual data values to the mean.
Ex: GPA. wi is the weight of an observation (let's say a 3-credit class). xi is the value of that observation
(like 3.5). So, We must ADD the PRODUCTS of Wi and Xi - not just the SUM of Xi. Then we DIVIDE by the
sum of the wis.
What is range? - correct answer ✔✔Range is the difference between the largest and smallest values in
an interval/ratio set of data.
What is quantile deviation? - correct answer ✔✔Quantile means equal portions of a data set. There are
several types of quantile:
>>> Median: divide data into 2 EQUAL sets.
>>> Quartiles: 4 equal sets - 25%
>>> Quintiles: 5 equal sets - 20%
>>> Percentiles: 100 equal sets - 1%
A quantile gives lots of information, including the median. The median is a data value at the middle
position. Since the median is a value that to the left side and to the right side we have an equal number
of values, then median has 50% of values to the left of it and 50% of values to the right of it.
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 BravelRadon. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $12.99. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
79650 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now
