Types of research studies
1
CASE STUDIES
EXPERIMENTS
DESIGN STUDIES
SURVEYS
MITE 6025 Session 2 (van Aalst)9/26/2013
What is an experiment?
 A study that tests a hypothesis about
a causal effect using at least two
independent samples
 Th...
Hypotheses
 A hypothesis is an educated guess
about what is going to happen during the
experiment
 It usually is based o...
Pre- and post-test
 Having experimental and control
samples not enough
 Also need to test both samples before
(pre-test)...
Simplest experimental design
Experimental Control
• Pretest on
dependent
variable
• Pretest on
other relevant
variables
• ...
Sample results for dependent
variable
Experimental Control
Pretest 50.1 (10.2) 48.4 (10.7)
Posttest 72.0 (8.5) 60.9 (10.9)...
Preparation (pretests)
 English proficiency test
 Chinese proficiency test
 General science achievement test
(Chinese)
...
Task design
 A reading task in English and Chinese
 Exactly the same content in both versions
 The same reading level i...
Finishing up (post-tests)
 Specific science post-test for both
samples
 Time for completion for both samples
MITE 6025 S...
Summary
Stage Experimental sample Control sample
Preparation • English proficiency
test
• Chinese proficiency
test
• Gener...
Sample results
Experimental (n = 30) Control (n = 30)
English test 672 (130) 520 (160)
Chinese test 620 (150) 590 (140)
Ge...
Extensions
 More than one treatment
 More dependent variables
 More control variables
MITE 6025 Session 2 (van Aalst) 1...
Quasi-experiments
 When used
 random selection and/or random assignment
are impossible
 Sample equivalence is difficult...
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MITE 6025 experiments

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Brief presentation intended to be a primer on experiments, to be used independently before students look at specific examples.

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MITE 6025 experiments

  1. 1. Types of research studies 1 CASE STUDIES EXPERIMENTS DESIGN STUDIES SURVEYS MITE 6025 Session 2 (van Aalst)9/26/2013
  2. 2. What is an experiment?  A study that tests a hypothesis about a causal effect using at least two independent samples  The experimental sample receives the intervention of interest  The control sample does not receive that intervention but is equivalent in all other respects 2 2.Experiments MITE 6025 Session 2 (van Aalst)9/26/2013
  3. 3. Hypotheses  A hypothesis is an educated guess about what is going to happen during the experiment  It usually is based on an implication (prediction) of a theory MITE 6025 Session 2 (van Aalst) 39/26/2013 2.Experiments
  4. 4. Pre- and post-test  Having experimental and control samples not enough  Also need to test both samples before (pre-test) and after the treatment (post-test) 4 MITE 6025 Session 2 (van Aalst)9/26/2013 2.Experiments
  5. 5. Simplest experimental design Experimental Control • Pretest on dependent variable • Pretest on other relevant variables • Pretest on dependent variable • Pretest on other relevant variables • Treatment • No treatment • Posttest on dependent variable • Posttest on dependent variable  Generalization to population  Random selection from population  Random assignment to conditions MITE 6025 Session 2 (van Aalst) 59/26/2013 2.Experiments
  6. 6. Sample results for dependent variable Experimental Control Pretest 50.1 (10.2) 48.4 (10.7) Posttest 72.0 (8.5) 60.9 (10.9)  The samples are similar at the pretest  The experimental sample outperforms the control sample on post-test  Need to calculate the probability of getting this effect MITE 6025 Session 2 (van Aalst) 69/26/2013 2.Experiments
  7. 7. Preparation (pretests)  English proficiency test  Chinese proficiency test  General science achievement test (Chinese)  Specific science test (same language as task) MITE 6025 Session 2 (van Aalst) 79/26/2013 2.Experiments
  8. 8. Task design  A reading task in English and Chinese  Exactly the same content in both versions  The same reading level in each language  Not too long MITE 6025 Session 2 (van Aalst) 89/26/2013 2.Experiments
  9. 9. Finishing up (post-tests)  Specific science post-test for both samples  Time for completion for both samples MITE 6025 Session 2 (van Aalst) 99/26/2013 2.Experiments
  10. 10. Summary Stage Experimental sample Control sample Preparation • English proficiency test • Chinese proficiency test • General science test (Chinese) • Specific science test (English) • English proficiency test • Chinese proficiency test • General science test (Chinese) • Specific science test (Chinese) intervention • Reading task (English) • Task completion time • Reading task (Chinese) • Task completion time Finishing up • Specific science test (English) • Specific science test (Chinese) MITE 6025 Session 2 (van Aalst) 109/26/2013 2.Experiments
  11. 11. Sample results Experimental (n = 30) Control (n = 30) English test 672 (130) 520 (160) Chinese test 620 (150) 590 (140) General science test 50.1 (10.0) 42.8 (10.3) Specific science pre-test 40.0 (9.5) 35.8 (10.2) Specific science posttest 60.1 (9.9) 57.9 (13.2) Completion time 17.5 (3.5) min 25.7 (3.9) min MITE 6025 Session 2 (van Aalst) 119/26/2013 2.Experiments
  12. 12. Extensions  More than one treatment  More dependent variables  More control variables MITE 6025 Session 2 (van Aalst) 129/26/2013 2.Experiments
  13. 13. Quasi-experiments  When used  random selection and/or random assignment are impossible  Sample equivalence is difficult to achieve  E.g. the use of in-tact classes  Assignment to classes not random  One class does the treatment, the other class does not  Classes may be taught by different teachers MITE 6025 Session 2 (van Aalst) 139/26/2013 2.Experiments

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