• requires a relatively smaller number of participants when compared with experimental designs as same participants are in all conditions beliefs about experimental procedures can be more difficult to control due to cues from experiencing different conditions • participant attrition • pairs of participants are matched on the basis of relevant personal characteristics that can influence the DV, then one member of each pair is randomly allocated to different conditions/groups • ensures each condition/group is fairly equivalent in spread of relevant personal characteristics that can influence the DV • participant attrition less likely • difficulty identifying all relevant variables (to be matched) • practical problems, e.g. time-consuming to identify and recruit participants who are sufficiently in the variable, pre-testing may be required and can lead to order effects requiring control • each participant is randomly allocated to either the experimental or control group and is in one group only • no effects across conditions to control • participant attrition less likely • less control over participant characteristics than repeated-measures and • often need a larger group of participants in order to lessen any differences between groups 2 For each of the following extraneous or potential confounding variables, rank the three experimental designs from 1 to 3 to indicate the extent to which the design controls the variable, as compared to the other designs. A ranking of 1 indicates greatest control and a ranking of 3 indicates least control. If appropriate, more than one design may be given the same ranking. Explain your choice of rankings. Variables Repeated-measures Matched-participants Independent-groups
• Bond – needs to be measurable, i.e. an attachment scale • Contact – Skin-to-skin? Breastfeeding? • What is your operational hypothesis for the experiment? • Newborns exposed to 30 minutes more skin-to-skin contact time with their mothers immediately after birth than the standard hospital time allotted will demonstrate a higher score on the X Attachment Scale. • What potential extraneous or confounding variables will it be important to control? • This small sample is not representative of the population. • willing to involve themselves in an experiment about their birth experience are also not representative of the population. • Are the mothers experienced mums or is this their first baby? • The nature of the birth may complicate the experience of attachment – natural, drugs, complications such as breech position, multiple births, caesarean. • What type of experimental design will you use? Explain your choice of design. • Independent groups would be the only feasible design here. The sample is too small for Matched-pairs and repeated-measures is out of the question due to the nature of birth! • If you find an acceptable significant difference in the results for the two groups (say, p ≤ 0.05), what conclusion would you draw? What generalisation would you make? • Conclusion – Newborns exposed to 30 minutes more skin-to-skin contact time with their mothers immediately after birth than the standard hospital time allotted have demonstrated a significantly higher score on the X Attachment Scale. • Generalisation – extra bonding time enhances attachment Learning Activity 1.26 (p. 78-9) Study 1 • voluntary participation, i.e. participants must freely choose to take part in research; must not be pressured to participate or experience negative consequences if choose not to • informed consent procedures, i.e. consent must be based on information about the nature and purpose of the research; use of an appropriate consent form etc. • professional conduct, i.e. the ‘lecturer’ who is responsible for the research must ensure all ethical guidelines are considered and followed (and is therefore responsible for the assistant’s conduct). Study 2 • use of deception: this is likely to be justifiable to ensure validity of the results but it also makes proper debriefing of particular relevance. Study 3