Stats 7
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What are parameters?
Population values

What are statistics?
Sample values

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 (Ybar)
 It is an unbiased estimate of the population mean

Which symbol represents the population mean?
µ

What is a more precise way of referring to variability?
Variance

How might one find an unbiased estimation of population variance?
 By dividing the sum of squares by the degrees of freedom (n1) 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?
σ^{2}

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?
zscores

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