Data recording, analysis and presentation

Nominal level data

Data recorded in named categories

Ordinal level data

Data recorded as points along a scale with not necessarily equal gaps

Interval level data

Data recorded as points along a scale with equal gaps

Measures of central tendancy

Typical/ average score from a data set

Measures of dispersion

Variance/ spread of scores in a data set

Standard deviation

Square root of the variance

Variance

Average of the squared differences from the mean

Range

Subtracting the smallest from the biggest value and adding one to the total

Significance level

p<0.05

Chi- square test

nominal data + independent measures

Spearman’s Rho

ordinal or interval data + correlations

Types of reliability

• Internal

  • consistency of results across a set

• External

  • extent to which a test produces the same results with the same people in the same situation

• Inter rater

  • researchers findings being similar

• Test retest

  • checking that results are valid through retesting

• Split half

  • comparing two halves of a test and seeing how well they correlate

Validity

• Internal

  • if the processes in a study achieve the intended measures

• Face

  • if the test if measuring what it is meant to

• Construct

  • if the thing being measured actually exists

• Concurrent

  • different measures of the thing result in the same circumstances at the same time

• Criterion

  • a measure of a thing predicting the value of another measure of the same thing

• Population

  • if the findings can be generalised to the entire population

• Ecological

  • if the findings are generalisable to real life

Ethical considerations

• Respect

  • informed consent

  • right to withdraw

  • confidentiality

• Competence

  • psychologists must work within their own capabilities

• Responsibility

  • protection of participants

  • debrief

• Integrity

  • deception

The median, mean and mode are…

all on the same point

In a positive distirbution curve the order is…

Mode, median, mean

In a negative distirbution curve the order is…

Mean, median, mode

Criteria for using a parametric test

Data is interval or ratio + data must have a normal distribution + variences must be similar

WilcOxon Signed-Rank test

ordinal + repeated measures

BiNomial Sign test

nominal + repeated measures

Spearmans Rho

ordinal and interval + correlation

Type 1 error

incorrectly rejecting null hypothesis

Type 2 error

incrorrectly accepting null hypothesis

calc < crit so results are significant

crit< calc so results are significant