IB PsychologyInternal AssessmentHigher Level 20% of final gradeStandard Level 25% of final grade

The Task Replicate an

experiment that manipulates an Independent Variable

Write a report conforming to IB guidelines

IA Differences between SL and HL

SL Weighting: 25% Replicate a published experimental

study; Characteristics of SL simple

experimental study: Limited in scope Involves the manipulation of only one

independent variable Involves the measurement of only one

dependent variable Requires the use and interpretation of the

descriptive statistics Does NOT require the use of inferential

statistics ; State the aim of the study.

HL Weighting: 20% HL students:

may undertake a replication or a modification of a published experimental study;

Are required to undertake more extensive background research related to their simple experimental study; 3 studies!!!

State an operationalized experimental hypothesis;

State an operationalized null hypothesis; Apply inferential statistical test to their

data and interpret the result of the test.

Internal Assessment CriteriaSL A – Introduction – 2 marks

B – Method: Design – 2 marks

C – Method: Participants – 2 marks

D – Method: Procedure – 2 marks

E – Results - 4 marks

F – Discussion – 6 marks

G – Presentation – 2 marks

Total: 20 marks

HLA – Introduction – 5 marks

B – Method: Design – 2 marks

C – Method: Participants – 2 marks

D – Method: Procedure – 2 marks

E – Results: Descriptive- 2 marks

F – Results: Inferential – 3 marks

G – Discussion – 8 marks

H – Citation of sources – 2 marks

I – Report format – 2 marks

Total: 28 marks

Step 1: Choosing an experiment to replicateGuidelines:

Ensure that the study has an IV that you can manipulate (not gender/age/culture) e.g. verbs, background noise.

Your experiment should be relatively easy to replicate, cognitive experiments concerning memory are best suited to the Internal Assessment.

You must clearly justify and operationalize your hypotheses.

Step 1: Choosing an experiment to replicateGuidelines:

You can not deceive, harm, or ask your participants to eat or drink any substances

You are not expected to conduct a ‘perfect’ experiment

You are not allowed to replicate experiments about/using: conformity & obedience, animal research, placebo, ingestion, deprivation, young children, quasi experiments, questionnaires.

Step 2: Locating Sources Try to locate a copy of

the original experiment on the internet

Find at least 3 other related studies – RESEARCH!

Analyze how all of these studies relate to your experiment – look at research design, findings etc

Avoid too many internet sources. No Wikipedia!!!

Student Advice Do not underestimate the amount of time

required to complete the IA Do not choose a study that is too obscure Scientific writing is “way harder” than you

think Think about the best time to hold your

experiment so that students will turn up Time management is the key!!!

Step 3 Modifying the Research Design You will have to

modify the original experiment Sampling Reduce the number

of variables Simplify the DV Use a different

statistical test to determine significance

Step 3 Modifying the Research Design cont’ Independent measures

design Vs. repeated measures design . (Be able to justify this in your report)

Independent measures is usually best as you don’t have to undertake counterbalancing to avoid the test-retest confounding variable

Step 4 Obtaining your sample of participants Student body will be

your target population It is best to select an

opportunity sample but you will have to justify why you did this. i.e. easier, Ppts more willing

An ideal sample is 50 students giving you two groups of 25.

If you have some no-shows you will still have 20 per group

Step 4 Obtaining your sample of participants Signed informed consent forms

must be obtained (You will provide a copy of the consent form in your appendix)

Students younger than 16 will require parental consent

You must keep all forms and ensure the confidentially of data

You must collect relevant bio-data from the participants e.g. age, first language etc. You will report any relevant characteristics

You must randomly assign participants to your groups!

Step 5 Ensuring Control The two groups in your experiment should

be treated exactly the same except for the IV

All instructions to the groups should be scripted to ensure they are identical

All other conditions should be identical as far as possible; Room, time of day etc. Control for extraneous variables!

Note any inadvertent differences in treatment and discuss this in your report

Step 6 Ethical Considerations Remind participants

that they are free to leave the experiment at any time

Debriefing: All participants must be informed of the results of your experiment

Step 7 Analyzing the Data – Descriptive Stats Use appropriate

descriptive statistics (one measure of central tendency and one measure of dispersion)

Present your data in both words and tabular form.

Step 8 Analyzing the Data – Inferential Stats Use non-parametric

statistical tests of significance (Mann Whitney U-test)

Your small sample size prohibits parametric tests like the t-test.

Best to calculate your test yourself but double check with online sites

Raw data and calculations should be included in the appendix

Which Inferential Test? HL only!!

Level of measureme

nt

Appropriate test for independent

samples

Appropriate test for

repeated measures

Nominal (Categories, frequency)

Chi-squared (X2 test)

Ordinal, Interval or Ratio

Mann-Whitney U test

Wilcoxon signed

ranks test

Writing Your Report You MUST follow the IB guidelines. Common omissions: no abstract; data not

displayed in three ways i.e. words, tables and graphs; sources not cited, no Works Sited page; no appendices (sample informed consent form, raw data, statistical test calculations, scripted instructions)

You must write like a social scientist. Avoid the 1st person “Basically I did this, then I did…..”