Applied Research Methods

What are longitudinal studies

Research is conducted over a long period of time to observe long term effects on a specific behaviour

What are cross-sectional studies

Data is gathered at one particular point in time

3 strengths of longitudinal studies

* range of methodology used - both data types
* Less chance of SDB - have to keep up changes over long period of time
* Able to observe long term effects

5 weaknesses of longitudinal studies

* expensive
* Time consuming
* Small groups of participants
* Drop out rates may be high
* More difficult to control extraneous variables

5 strengths of cross-sectional studies

* less expensive
* Larger participant groups
* Quicker
* Lower participant drop out rates
* Easier to control extraneous variables

3 weaknesses of cross-sectional studies

* low amount of methodology used
* More chance of SDB
* Only able to look at one point of time

What does CT scan stand for

Computed axial tomography

What are CT scans

A set of x-rays combined together to form 2D or 3D images

How are CT scans with contrast taken

Radioactive dye is injected into the patient before thr scan

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What areas are CT scans with contrast used for

Brain and soft tissues

How do CT scans work

A series of X-ray beams pass through the head creating cross-sectional images of the brain showing the structure but not the function

What is an example of a CT scan in research

Johnstone et al (1976)

What does PET scans stand for

Position emission tomography

What are patients given before PET scans

Radioactive glucose (sugar)

What areas of the brain require the most glucose

Those that are most active

What do the detectors in the PET scanner do

Highlight the most active areas of the brain allowing an in-depth image of what the brain activity is like

What is an example of a PET scan in research

Raine et al (1997)

What does MRI scan stand for

Magnetic resonance imaging

What does an MRI scan do

A magnetic field surrounding the brain causes the atoms of the brain to change and emit various radio signals

What does the detector in the MRI scan do

Reads the signals and map the structure of the brain

2 strengths of PET scans

* allows researchers to see chemical activity and so they can distinguish between benign and malignant tumours
* Look at more active brain areas

3 weaknesses of PET scans

* costly to run and maintain
* Not as precise
* Radioactive dye needed (can only be administered a few times)

2 strengths of CT scans

* high quality images
* Can reveal structures in the brain that appear abnormal

2 weakness of CT scans

* only provide a researcher with the structure of the brain
* Exposure to radiation

2 strengths of MRI scans

* more detailed than CT
* Does not expose patients to radiation

2 weaknesses of MRI scans

* long
* Uncomfortable + any movement may result in an unclear image

Define reliability

The extent to which a method of measurement or study can produce consistent findings across situations or times

3 factors that may affect reliability

* lack of control
* Use of standardised procedures
* Use of objective data

Define internal reliability

The extent to which a test or measure is consistent within itself

How is internal reliability assessed

Split half method w

What is the split half method

An individuals responses are split in half and compared

Define external reliability

The extent to which a test produces consistent results over several occasions

How is external reliability tested

Test-retest method

What is the test-retest method

A group of participants are given the same test sometime later

Define interrater reliability

The extent to which different observers are able to write and record the same behaviour

What is observer bias

Interpretation of behaviour may be bias either consciously or unconsciously

define validity

whether something measures what it claims to measure

define internal validity

the findings are accurate and the effects on the DV are caused by the IV so the study measures what it intends to measure

define external validity

whether the study presents a true picture of real-life behaviours and whether the findings would apply to different places, different times or different people

what are the 3 types of external validity

* population validity
* ecological validity
* historical validity

define population validity

are the findings generalisable to all people?

define ecological validity

is the research generalisable to everyday life?

define historical validity

if the study was conducted a long time ago is it still generalisable to today’s society

what are the 5 methods of checking the internal or external validity of a study

* face validity
* predictive validity
* content validity
* concurrent validity
* construct validity

define face validity

does the test appear to measure what it claims? tests where the purpose is clear even to naïve respondents have a high face validity

define predictive validity

do the scores predict what you expect them to predict

define content validity

does your measure accurately and fairly measure your intended content? decides whether it is a fair test

define concurrent validity

how does the proposed measurement for the behaviour match with a previously validated one on the same topic? high = similar results

define construct validity

does the test measure the target construct?

what needs to be included in a 15 mark experiment planning question (9)

* experimental hypothesis
* type of experimental method/design
* setting (specific)
* sample
* operationalisation
* extraneous variables
* checking reliability (internal + external)
* checking validity (internal + external)
* ethical issues

what are the 3 measures of central tendency

mean, median, mode

what are the 2 measures of dispersion

range, standard deviation

how to calculate standard deviation

1. find the mean of the results
2. create a table with the headings n, x, x - xbar, (x-xbar)2
3. fill in participant number in n column
4. fill out results in x column
5. find the difference between x (score) and xbar (mean) for each participant
6. square each answer for previous step
7. find the sum of all squared values
8. divide the previous value by n (participant number) if you have complete data and n-1 if you have incomplete data
9. square root answer

1 strength of using the mean

* most detailed

2 weaknesses of using the mean

* affected by anomalies
* cannot be used for nominal data

1 strength of using the median

* not affected by anomalies

2 weaknesses of using the median

* not very exact
* cannot be used for nominal data

3 strengths of using the mode

* can be used for nominal data
* quick and easy
* not affected by anomalies

1 weakness of using the mode

* issue when there is several/no modes

1 strength of using the range

* quick and easy

3 weaknesses of using the range

* affected by anomalies
* all scores are not accounted for
* does not give an idea of how close scores are to the average

3 strengths of using standard deviation

* all scores considered
* gives idea of how close scores are to average
* most detailed and precise

2 weaknesses of using standard deviation

* takes a long time
* affected by anomalies (when working out xbar)

what is nominal data

categories of data

what is ordinal data

data is on order but we don’t know how far apart each participant is

what is interval data

intervals between participants are known

what is ratio data

intervals between each participant are known and there is a true 0 point i.e. data cannot go below zero e.g. money

how is frequency worked out from a histogram

find the area of the bar

what are distribution curves

linear representations of data that include a mean, median and modal score

what are the 3 types of distribution curve

* normal distribution
* positive (right) skewed distribution
* negative (left) skewed distribution

how to recognise normal distribution

mean, median and mode in same position

what % of people will be 1 standard deviation away from the mean in normal distribution

68\.26% (32.13% on each side)

how to recognise positive (left) skewed data

the mode is lower than the mean

how to recognise negative (right) skewed distribution

the mode is higher than the mean

how to work out if a sign test is used (flow chart)

difference → nominal data → repeated measures

how to work out if chi squared has been used (flow chart)

difference → nominal data → independent groups

how to work out if wilcoxon matched pairs has been used (flow chart)

difference → ordinal data → repeated measures

how to work out if mann whitney u has been used (flow chart)

difference → ordinal data → independent groups

hoe to work if spearman’s rank (rho) has been used (flow chart)

correlational → ordinal data

what is the value of n (no. of participants) if any participants show no change

n - number of participants showing no change

what is the notation for a sign test

s

what is the notation for chi squared

x2

what is the notation for wilcoxon matched pairs

t

what is the notation for mann whitney u

u

what is the notation for spearman’s rank

rho

what type of hypothesis is a one-tailed test

directional

what type of hypothesis is a two-tailed test

non-directional

what probability value is used for a directional hypothesis in a critical values table

0\.05

what probability value is used for a non-directional hypothesis in a critical values table

0\.025

how do we know if results are statistically significant in chi-squared and spearman’s rank (r up rule)

observed value ≥ critical value

how do we know if results are statistically significant in sign, wilcoxon, and mann whitney (r up rule)

observed value ≤ critical value