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What are parameters?
What are statistics?
What qualities should estimators possess?
- They should be unbiased
- They should be efficient (relatively stable across estimates)
What is the best estimate of population mean?
- The sample mean (Y-bar)
- It is an unbiased estimate of the population mean
Which symbol represents the population mean?
What is a more precise way of referring to variability?
How might one find an unbiased estimation of population variance?
- By dividing the sum of squares by the degrees of freedom (n-1) rather than n
- This is called the sample variance
- Dividing by n might cause us to underestimate the true population value
When is dividing by simply n acceptable?
When describing sample variance
What is the best estimation of population variance?
The sample variance once the sum of squares has been divided by the degrees of freedom
Which symbol represents population variance?
What do box plots provide?
A simple graphical representation of data that capture features of both location and spread of scores in a distribution
Label the box plot
- 1: Minimum
- 2: Q1
- 3: Median
- 4: Q2
- 5: Maximum
Identify the outliers
What are the criterions we use for identifying outliers?
- Any value that lies 1.5x the interquartile range above the third quartile or below the first
- This is used by minitab, and the outliers are plotted above or below the plot
Give an example of a linear transformation
The conversion of inches into centimetres
Give the equation for a linear transformation
- K denotes a constant
- C denotes a constraint
- Y denotes the data that are manipulated
How might one find standard scores?
- Scores are transformed into a common scale so the mean is 0 and the standard deviation is 1
- The following equation is employed:
What is the word equation for calculating raw scores into standard scores?
What is the unit of measurement for standard scores?
The standard deviation
If they are normally distributed, what are standard scores referred to as?
Which two linear transformations are involved in finding standard scores?
- A constant (the mean) is subtracted in order to find deviation scores
- The deviation scores are divided by another constant (the standard deviation)
How are new standard scores produced?
- The original mean is subtracted from each score
- The total is divided by the original standard deviation to produce standard scores
- Each new standard score is multiplied by the new standard deviation and the new mean is added