Data analysis and reports

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  • 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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