• An experiment uses logic& symbol found in Natural Sciences• It is usually conducted in laboratories• It usually involves less number of people• It addresses well focused questions
• It is most effective for explanatory research• The experimenter experiments a question• The experimenter divides the population into two groups
Before the upcoming elections ECP (ElectionCommission of Pakistan)to check the newsystem is fair or not used computerised system inthe by elections of two constituencies PP126 andPP 143 and found that the system is fair.
• Experimental research is a research in which we use logic & symbols found in natural science• An experiment means, “modifying something in a situation, then comparing an outcome to what existed without the modification”
• I try to start my car. To my surprise, it does not start.• I “experiment” by cleaning off the battery connections, then try to start it again.• I modified something(cleaned the connections) and compared the outcome (weather the car started) to previous situation (It didn’t start).
I drew the hypothesis• Once the terminals is cleaned off the car will start.
This illustrates three things researchers do inexperimental research:• Begin with a hypothesis• Modify something in a situation• Compare outcomes with and without the modification
Research questions appropriate for experimental research
• New researchers often asks which research techniques best fits which problem• It is difficult answer these questions because there is no fixed match between problem and technique
The answer is:• Make an informed judgment.• You can develop the judgment by:• reading research reports• understanding the strengths & weakness of different techniques• Assisting more experiences researches with their research training• Practical Experience
• Random assignment is a method for assigning cases (e.g., individuals, organizations, etc.) to groups for the purpose of making comparisons.• It is a way to divide a collection of cases into two or more groups in order to increase ones confidence that the groups do not differ in a systematic way.• It is a mechanical method; the assignment is automatic, and the researchers cannot assignments on the basis of personnel preference or the features of specific cases.
• Random assignment is random in statistical or mathematical sense.• Random selection lets researcher calculate the odds that a specific case will be sorted into one group over another.• For example, A researcher wants to research the IQ level between the ages 20, 30,50. he randomly makes the group of 50 each
• Treatment (stimulus or manipulation) is what a researcher modifies.• In most experiments, a researcher creates a situation and then modifies it.• The term originated from the discipline of medicine in which a physician treats a patient.
• On such pattern a researcher develops a measuring instrument or indicator• Example; (Survey questions),then apply it to a person or a case.• In experiment researcher “measure” independent variable by creating a situation
• For example; the independent variable is degree of fear or anxiety”, the levels are high fear and low fear.• Instead of asking subject weather they are fearful the experimenters puts subjects into high fear or low fear.• They measure the independent variable by manipulating conditions so that some subjects feels lots of fear and others feel little
• Dependent variable or outcomes in experimental research are the physical conditions, social behaviors, attitudes, feeling, or beliefs of subjects that change in response to a treatment.• Dependents variables can be measured by paper-and-pencil indicators, observations, interviews, or physiological responses(e.g., heart attack and spreading pain)
• The posttest is the measurement of the dependent variable after treatment has been introduced into experimental group (e.g., children of divorcee’s have high rate of angriness while children of married couples have low rate of angriness)• Mostly experimental researchers divides subjects into two groups
• Begin with a straightforward hypothesis that is appropriate for experimental research• Decide on an experimental design that will test the hypothesis within practical limitations• Decide how to introduce a treatment or create a situation that induces the independent variable
• Develop a valid and reliable measure of the dependent variable.• Set up an experimental setting and conduct a pilot test of the treatment and dependent variable measures.• Locate appropriate subjects or cases.
• Randomly assign subjects to groups (if random assignment is used in the chosen research design) and give careful instructions.• Gather data for the pretest measure of the dependent variable for all groups (if a pretest is used in the chosen design)
• Introduce the treatment to the experimental group only (or to relevant groups if there are multiple experimental groups) and moniter all groups• Gather data for posttest measure of the dependent variable
• Debrief the subjects by informing them of the true purpose and reasons for the experiments. Ask subjects what they thought was occuring. Debriefing is crucial when subjects have been deceived about some aspect of the experiment.
• Examine data collected and make comparisons between different groups. Where appropriate, use statistics and graphs to determine wether the hypothesis is supported
• An experimental design that has random assignment, a control group, an experimental group, and a pretest and posttest for each group.
• For Example; The experimenter gives 40 newly hired wait staff an identical two-hour training session and instructs them to follow a script in which they are not to introduce themselves by first name and not to return during the meal to check on the customers.
• The experimenter divides them into two equal groups of 20 randomly.• The experimenter records the amount of tips of all the subjects for a month (pretest).• The experimenter retains the group 1 at resturant 1 (experimental Group)• The experimenters asks them to introduce themselves by first name for 8mins (treatment)
• The group 2 continue their work without an introduction or checking during the meal(control group)• Over the second month the amount of tips for both groups is recorded (posttest)
• Experimental design that that lack randonm assignment or use shortcuts and are much weaker than the classical experimental design. They are be substituted in situations in which an experimenter cannot use all the features of a classical experimental design, but have weaker internal validity
• An experimental Groups with two groups, no random assignment and only a posttest
What is Quasi Experimental and Special Designs?
• Experimental designs that are stronger than pre experimental designs. They are variations on the classical experimental design and are used in special situations or when an experimenter has limited control over independent variable
• This is identical to the static group comparison, with one exception: The groups are randomly assigned. It has all the parts of the classical design except a pretest. The random assignment reduces the chance that the groups differed before the treatment, but without a pretest, a researcher cannot be as certain that the groups began the same an the independent variable.
• An experimental design in which the dependent variable is measured periodically across many time points, and the treatment occurs in the midest of such measures, often only once.e.g.: anxiety and depression test over an anxiety patient and its treatment.
• An experimental design in which there are several repeated pretests, posttests, and treatments for one group often over a period of time.• Example; the experimenter experiments that the people who do not wear helmets can have swear head injury. The bill was passed on 1975 repelled in 1981 and reinstated in 1998.
• An experimental design used to examne whether the order or sequence in which subjects receive multiple versions of the treatment has an effect• Example; A geography teacher has three units to teach students: map reading, using a compass, LL system (longitudinal and latitudinal system )
• In one class he used one method and in second class he used in another class and in class three he used both system in the end he took end test to check weather the learning environment improved or not.
• An experimental design in which subjects are randomly assigned to two control groups and two experimental groups. Only one experimental group and one control group receive a pretest. All four Groups receive a posttest.
• Example; A mental health worker want to determine whether a new training method improves clients’ copying skills. the worker measures coping skills with a 20 minutes test of reactions to stressful evens. Because the clients might learn coping skills from taking the test itself, a Solomon four-group design is used.
• The mental health worker divides the clients into four groups.• Two groups receive pretest. One of them gets new training method an the other gets old training method. Another two groups receive no pretest.• All four groups are given the same posttest and posttest results are compared.
• An effect of two independent variables operating simultaneously and in combination on a dependent variable. It is a larger effect than occurs from the sum of each independent variable working separately
Internal Validity External validityWhat is Internal and external validity?
Internal Validity• The ability of experimenters to strengthen the logical rigor f a casual explanation by eliminating potential alternative explanations for an association between the treatment and dependent variable through an experimental design• Variables other than the treatment that effects the dependent variable are threats to internal validity.
External Validity• The ability to generalize the findings beyond a specific study
• A field experiment applies the scientific method to experimentally examine an intervention in the real world (or as many experimentalists like to say, naturally occurring environments) rather than in the laboratory. Field experiments, like lab experiments, generally randomize subjects (or other sampling units) into treatment and control groups and compare outcomes between these groups.• Examples include:• Clinical trials of pharmaceuticals are one example of field experiments.• Economists have used field experiments to analyze discrimination, health care programs, charitable fundraising, education, information aggregation in markets, and microfinance programs.• Engineers often conduct field tests of prototype products to validate earlier laboratory tests and to obtain broader feedback.