WEEK 6 Flashcards

PROBABILITY AND DISTRIBUTION

1
Q

The ‘Normal Distribution’ Key Features:

A
  • Peak in the middle
    -Tails off symmetrically at either side of the peak
    -Bell shaped curve
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2
Q

What is the definition of ‘Skewness’:

A
  • The extent to which your frequency histogram is lopsided rather than symmetrical
    -Skew suggest data that deviates from a normal distribution
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3
Q

Types of Skewed Distributions

A
  1. positively skewed distribution: The peak is shifted to the left towards the low numbers
    2.negatively skewed distributions: The peak is shifted to the right towards the high numbers

Bimodal: 2 peaks in a distribution
Multimodal: Two major peaks in a distribution

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4
Q

Kurtosis: Leptokurtic
-a measure of peak and flatness, or steep and shallowness

A

Leptokurtic: Higher kurtosis/ very peaked distribution

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5
Q

Kurtosis: Platykurtic

A

Lower kurtosis/ flat distribution

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6
Q

Kurtosis: mesokurtic

A

Between the two extremes of peakedness and flatness

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7
Q

What is the Floor and Ceiling Effect?

A
  • Floor: when a measure produces most values near the bottom end of a scale

-Ceiling: when a measure produces most values near the top end of a scale

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8
Q

The Standard Normal Distribution

A
  • Normal shaped distribution with a mean of 0 and a standard deviation of 1
  • the total area under the curve is 1/ 100%
  • To compare scores from different samples we convert our scores into standardised scores, known as Z scores
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9
Q

Z scores

A

Z score: tells us how many standard deviations above or below the mean a score is
- To calculate the z score, subtract the sample mean from the score and then divide by the sample standard deviation

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10
Q

Identifying Outliers using Box Plots

A
  • SPSS identifies
  • outliers with a o
    -extreme scores
    -Check for errors in data entry
    -REPORT IT
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11
Q
A
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