This document discusses experimental research designs. It provides descriptions of various research designs including true experimental designs like the pretest-posttest control group design and Solomon four-group design. It also discusses quasi-experimental designs like the nonequivalent-groups design and time series design. Factorial designs are also mentioned. Key aspects of experimental research designs discussed include internal and external validity, controlling extraneous variables, and establishing causality between independent and dependent variables.

1. Jierah Sabadlab

2. a process of observation , to
be carried out in a situation
expressly brought about for a
purpose
especially suited for
hypothesis testing
taking action observing the consequences
of that action
involves

3.  provides a systematic and logical method
 answers the question “If this is done under carefully
conditions, what will happen?”
 provides a method of hypothesis testing
 a classic method of the science laboratory where elements
manipulated and effects observed can be controlled

4. Commonly used in sciences such as
1. Sociology
2. Psychology
3. Physics
4. Chemistry
5. Biology
6. Medicine

5. If an instance in which the phenomenon under investigation occurs, and an
instance in which it does not occur have every circumstance in common save one,
that one occurring only in the former, the circumstance in which alone the two
instances differ is the effect, or the cause, or an indispensable part of the cause of
the phenomenon. (Mill, 1873, p. 222)
“Law of the Single Variable”
John Stuart Mill, 1873

6.  exposed to the influence of the factor under
considertaion
 very similar to experimental group, except that they
are NOT exposed

7.  participants don’t know what they are taking
 ensures that changes in dependent variable actually result
from independent variable and are not psychologically-
based

8.  pointed to the necessity of control groups
 Workers were responding more to the attention than to the
improved working conditions
light intensity
worker output
light intensity
worker output

9. are the conditions or characteristics that the experimenter
manipulates, controls or obeserves

10.  conditions or characteristics that apper, disappear or
change as the experimenter introduces, removes or
changes independent variables
 Might be physical conditions, social behavior, attitudes,
feelings or beliefs
 the outcome
 “The Effect”

11.  conditions or characteristics that the experimenter
manipulates or controls in his or her attempt to ascertain
their relationship or phenomena
 “The Cause”

12. Treatment Organismic / Attribute
factors that the
experimenter
manipulates and to
which he or she assigns
subjects
those characteristics
that cannot be altered by
the experiment

13. Example
8-year-old girls show greater reading achievement than
8-year-old boys
Answer
Organismic or Attribute Variable

14. Intervening Extraneous
 hard to observe
 it involves indivual’s
feelings
 readily observed
 more easily controlled

15. Controlling Extraneous Variables
 it can be controlled by eliminating them completely

16. Controlling Extraneous Variables
 “Random assignment”
2 groups tossing a coin
more than 2 groups dice or table of random numbers

17.  most effective method of eliminating systematic bias
and of minimizing the effect of extraneous variables
 selecting pairs of individual with identical or nearly
identical characteristics
 “matched randomization

18.  variances of groups are nearly equal as possible
 the researcher must decide how much departure
from equality can be tolerated without loss of
satisfactory control

19.  Subjects are intially measured in terms of the dependent
variable prior to association with the independent variable
(pretested)
 Then, they are exposed to the independent variable
 Finally, they are re-measured in terms of the dependent
variable (posttested)

20.  Differences noted between the measurements on the
dependent variables are attributed to influence of the
independent variable

21. Threats to Internal Validity
 factors that may not reflect in experiment
1. Maturation
2. History
3. Testing
4. Unstable Instrumentation
5. Statistical Regression

22. 6. Selection Bias
7. Interaction of Selection and Maturation
8. Experimental Mortality
9. Experimenter Bias
Threats to Internal Validity

23.  neither the subjects nor the experimenters know which is
the experimental group and which is the control group
 Experimenters may be more likely to “observe”
improvements among those who received the drug

24. Threats to External Validity
1. Interference of prior treatment
2. The artificiality of the experimental setting
3. Interaction effect of testing
4. Interaction of selection and treatment
5. The extent of treatment verification

25.  blueprint of the procedures that enable the
reasercher to test hypotheses by reaching valid
conclusions about realtionships between
independent and dependent variables

26.  least adequate of designs is characterized by lack of
a control group or a failure to provide for the
equivalence of a control group

27. One-Shot Design
 In this design, a single experimental group is exposed to a
treatment and observations are made after the
implementation on that treatment
 There is no random assignment of subjects to the
experimental group and no control group at all.

28. One-Group Pretest-Posttest
Design
 simplest type where only the experiment group is selected
as the study subjects
 A pretest observation of the dependant variables is made
before implementation of the treatment to the selected
group, the treatment is administered and finally a posttest
observation of dependent variables is carried out to assess
the effect of the greatment on the group.

29.  very simple and covenient to conduct studies in natural
settings
 most suitable design for the beginners in the field of
experimental research

30.  Considered a very weak
 has very little control over the research
 has higher threat to internal validity of research and may
have a selection bias, which can be very serious threats

31.  researchers havecomplete control over the
extraneous variable and can predict confidently that
the observed effect on the dependable variable is
only due to the manipulation of the independent
variable

32. Posttest-Only, Equivalent-
Groups Design
 Composed of two randomly assigned group; experimental
and control, but neither of which is pretested before the
implementation of treatment on the experimental group
 This design can be helpful in situations where it is not
possible to pretest the subjects.

33. Pretest - Posttest Equivalent-
Groups Design
 In this design, subjects are randomly assigned to either the
experimental or the control group
 The treatment is carried out on experiment group only and
after treatment, observation of dependent variable is made
on both groups to examine the effect of the manipulation of
independent variable on dependent variable.

34. Solomon Four-Group Design
 In this design, there are two experimental groups and two
control groups.
 Believed to be most prestigous experimental reaserch
design because it minimizes the threat to internal and
external validity.

35.  considered the most powerful designs to establish the
causal relationship between independent and dependent
variables
 The controlled environment in which the study is conducted
can yield a greater degree of purity in observation.

36.  Most of the times, the results of experimental researc
designs cannot be replicated in studies conducted on
human beings due to ethical problems.
 Many of the human variables neither have valid measurable
criteria nor instruments to measure them.

37.  Involves the manipulation of independent variable to
observe the effect on dependent variable, but it lacks
at least one of the two characteristics of the true
experimental design; randomization or control group

38. Causality - effect of the independent variable on
dependent variable

39. Nonequivalent-Groups Design
 In this design, experimental and control groups are selected
without randomization and dependent variables are
observed in experimental as well as control groups before
the intervention
 Later, the experimental group receives treatment and after
that posttest observation of dependant variables is carried
out for both the groups to assess the effect of treatment on
experiment group.

40. Time Series Design
 This design is useful when the experimener wants to
measure the effects of a treatment over a long period of
time
 Generally, it is a single-subject reaserach in which the
researcher carries out an experiment on an individual or on
a small number of individuals, by alternating between
administering and then withdrawing the treatment to
determine the effectiveness of the intervention.

41. Factorial Design
 In this design, researcher manipulates two or more
independent variables simultaneously to observe their
effects on the dependent variables.
 This is useful when there are more than two independent
variables, called factors to be tested

42.  most frequently used because they are more feasible and
practical to conduct research studies
 more suitable for real-world natural setting than true
experimental research designs

43.  There is no control over extraneous variables influencing the
dependent variables
 The absence of control group or lack of control over the
resaerch setting makes the results of this design less reliable
and weak for the establishment of causal relationship
between independent and dependent variables.