Meta analysis

Question 1

meta analysis

Answer 1

• technique of analysis
• using results from different studies about the same issue & studying them as a whole
• to look for an overall picture about the area of study
• uses studies that have already been carried out
• with research methods chosen and separate analysis already done

Question 2

why are meta analysis used

Answer 2

• if a number of studies find the same answer & those studies are then analysed together
• answer becomes stronger
• as studies support one another
• adjudicate where studies find different answers

Question 3

what type of data does meta analysis use

Answer 3

secondary data

Question 4

primary data

Answer 4

collected directly, first hand by researcher

Question 5

secondary data

Answer 5

already collected from a different researcher & used for a different piece of research

Question 6

strengths of secondary data

Answer 6

• cheaper, as it already exists
• often involves larger sample sizes, reducing chances of anomalies skewing data
• allows for analysis of trends over time
• researchers own bias is less likely to influence the data
• ethical = no participants needed

Question 7

weaknesses of secondary data

Answer 7

• has been gathered for another purpose & already analysed, bringing subjectivity = may not be valid for 2nd purpose
• may lack credibility
• may have been gathered a long time ago, so conclusions drawn from this data may be invalid, ie. cultures change over time
• researcher has a lack of control over data collection methods - data may not have been collected well so less valid

Question 8

steps involved in meta analysis

Answer 8

• define research question
• perform literature research
• select studies
• extract the data
• analyse the data
• report the results

Question 9

when was meta analysis used in criminal psychology

Answer 9

Steblay et al 1999 - to investigate pre trial publicity

Question 10

over past 30 years, what empirical studies into PTP have been conducted -

Answer 10

• Steblay reviewed 44 empirical studies that examined effects of negative ptp on juror decision making
• including simulated jury trials, survey studies, experiments
• all focused on how exposure to PTP affects verdict decisions

Question 11

what issues do the studies Steblay reviewed pose to readers who want to ascertain whether there is a relationship between PTP & juror decisions

Answer 11

• sample types (students vs jury eligible adults)
• type of PTP (real vs fictitious)
• crime severity
• timing of verdict assessment
• making it difficult to draw firm conclusions about true effect of PTP across contexts

Question 12

what hypothesis was common to the studies Steblay reviewed

Answer 12

• common hypothesis = exposure to negative ptp increases the likelihood of a guilty verdict
• findings found the meta analysis supported this hypothesis

Question 13

Steblay findings

Answer 13

• jurors exposed to negative ptp were significantly more likely to convict compared to those not exposed
• average conviction rate was 59.1% in ptp conditions vs 45.0% in control groups

Question 14

what do meta analysis show us

Answer 14

• provide the means to combine results from multiple studies to determine
• whether a consistent effect exists
• magnitude of the effect
• moderator variables that influence the effect

Question 15

what methodological issues to meta analysis help to overcome

Answer 15

• small sample sizes in individual studies
• inconsistent methodologies
• variability in outcomes
• low statistical power
• allows researchers to systematically evaluate patterns across a broader dataset

Question 16

what other meta analyses has Steblay conducted

Answer 16

• weapon focus effect 1992
• eyewitness identification accuracy

Question 17

why may conducting meta analysis be useful when considering effects of PTP

Answer 17

• determine whether ptp consistently effects juror decisions
• measure how strong effect is
• identify which conditions increase or reduce the effect
• address methodological inconsistencies across studies

Question 18

what are the 4 goals Steblays meta analysis for his research into PTP

Answer 18

• determine whether negative PTP affects verdicts
• identify conditions that influence the effect
• evaluate how methodological variations impact findings
• suggest future research directions

Question 18

how did Steblay find his literature

Answer 18

• published articles
• unpublished dissertations
• conference papers
• direct contact with researchers
• he included studies that offered quantifiable data on verdict outcomes following negative PTP exposure

Question 19

type & level of PTP in studies reviewed, but what was the dependent variable in the studies Steblay used

Answer 19

• verdict judgement
• whether ppts found defendant guilty or not guilty

Question 20

describe sample of literature used by Steblay

Answer 20

• 44 empirical tests
• total of 5,755 participants
• included both student & jury eligible adult samples
• varied in crime type, PTP format & whether real or fictional PTP was used

Question 21

outline findings of Steblays meta analysis

Answer 21

• negative ptp significantly increased conviction rates (59.1% vs 45.0%)
• effect was robust even across different study designs
• larger effect was found when :
• real PTP was used
• community members were participants
• the effect remained even after jury deliberation & other safeguards
• overall PTP was shown to have a moderate, consistent biasing effect on juror decision making

Question 22

generalisability

Answer 22

• results may be generalised to a wider populations
• as a larger number of studies may involve different participants & settings being analysed

Question 23

reliability

Answer 23

• researchers often do not include any unpublished work
• meaning all findings that are drawn upon have been peer reviewed

Question 24

applications

Answer 24

- meta analysis focus on effect sizes - so we can establish the impact of PTP on juror opinions - adapt courtroom proceedings

Question 25

validity - strengths

Answer 25

- collect a large amount of data from a vast array of different areas - gaining a huge overall sample very quickly

Question 26

weaknesses - validity

Answer 26

- researchers aren't involved in gathering data directly so undisclosed methodological issues may affect conclusions - uses secondary data that has been gathered for another purpose and has already been analysed, may be subjective to previous researcher & not fit for 2nd purpose - publication bias - may produce unintentionally biased results which include using an incomplete set of keywords or varying strategies to search databases, & search engine used can be a factor = selection bias

Question 27

publication bias

Answer 27

- tendency for studies with statistically significant results to be published more readily than those with non significant findings - meta analysis can be overestimating effect sizes

Question 28

ethics

Answer 28

- researchers do not carry research out themselves - avoiding any concerns with regards to how participants were treated