Topic 1 - Descriptive Statistics Flashcards
(12 cards)
1
Q
What is the population
A
- Represents the target of statsitical inference
2
Q
What is the sample
A
- A subset of the population
3
Q
Why dont we collect data from the population
A
- It is impractical and expensive
4
Q
How is the mean calculated
A
- The sum of all data entrys divided by the number of data entrys
- The population mean is denoted µ
5
Q
How is the median calculated
A
- The value thats in the centre of an ordered sample
6
Q
How is the mode calculated
A
- The most frequent value in the data
7
Q
What is the issue with central tendency methods
A
- Only locates center of the distribution of the data and says nothing about variation or dispersion
8
Q
What can we use the measure the spread of a variable
A
- Sample variance
- s^2 = 1/n-1 * sum of (yi - mean)^2
9
Q
What is the most commonly used measure of dispersion
A
- Standard deviation
- square root of s^2 formula
10
Q
How are variance and standard deviation denoted with respect to the population
A
- σ^2 and σ
11
Q
What labels are used to refer to population and sample
A
- Sample -> Statistic
- Population -> Parameter
12
Q
What variables are used for number of objects and calculating Mean, Var, S.D for population and Sample
A
- Pop objects = N
- Samp objects = n
- Pop mean = mu
- Samp mean = y bar
- Pop var = sigma^2
- Samp var = s^2
- Pop S.D = sigma
- Samp S.D = s
