# Data analysis and reports

• Created by: ava.scott
• Created on: 25-05-15 13:19

## GRAPHS 7 points + freq.polygons 3

Remember:

• title
• labelled axes
• sensible scale
• bar charts have gaps
• histograms dont have gaps

Frequency polygons

• only central point is plotted
• points are joined
• data is continous
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## Inferential stats

Inferential statistics assess probability of the results being down to chance.

If the results are cause by a genuine effect, they are significant.

The inferential tests allows us to reject or accept the null hypothesis.

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## Null hypothesis

• Always non-directional.
• There will be no difference between conditions, or no correlation.
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## Inferential tests 3 points

• Looking for a difference or a correlation
• Independent groups or repeated measures/matched pairs
• nominal data or ordinal/interval?
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## WHICH TEST?

Spearmans Rho

• looking for a correlation
• independent groups
• atleast ordinal data

Wilcoxon

• Repeated measures/matched pairs
• looking for a difference
• atleast ordinal data

Mann-whitney U

• Independent groups design
• Looking for a difference
• Atleast ordinal data

Chi2- NOMINAL data, difference and indepedent groups

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## Assessing significance

Expression of P- probability

< means less than

<< means much less than

~ means approx the same as

Alpha level

usually p = <0.05

socially sensitive p=<0.01

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## Type 1 and 2 errors

Type 1

• false positive
• null hypothesis is rejected incorrectly
• all inferential tests refer to this

Type 2

• false negative
• null hypothesis retained incorrectly
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## Reports: features

• Title
• Abstract
• summarises the method and findings of a study
• so other researchers can choose to read the whole report or not
• Introduction
• summarises previous research
• outlins objective and purpose of the research
• importance of the research- why it was done.
• Method - design, sample, materials, prcedure
• Findings/results
• inc. stats
• Conclusions
• Discussion
• applications
• reliability and validity
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