Reliable
If an experiment can be replicated.
Parsimony (Occaim's Razor)
The finding should be explained and interprited in the simplest and most
... [Show More] economic way
Experiment
The most common type of research. The researcher has control over all relevant variables. Usually conducted in Labs or high control settings.
Confounding
When undesirable variable enter the experiment.
Independent variable (IV)
The variable that the experimenter manipulates
Dependent variable (DV)
The result, the data, the scores, some form of human response.
Control Group
Group of people who don't receive any form of the IV or experimental variable
Experimental Group
Group of people who do receive the IV or experimental variable.
Random Sampling
Every member of the population has an equal probability of being selected for the study and the selection of one member of the population has no effect on the selection of an other member.
Random assignment
Subjects are randomly assigned to the experimental and control groups.
True Experiment
Every member has an equal chance of selection AND are randomly assigned to groups. Rare in most studies.
Quasi Experiment
Any research that fails to use random assignment or lacks a control group. All intact group studies.
Stratified Sampling
People are selected from sub-groups.
Proportional Stratified Sampling
The data reflects the pattern that occurs naturally. i.e. the population you are working with is 1/2 black and 1/2 white. Your study would have 1/2 black 1/2 white
Cluster Sampling
A naturally existing group is selected. i.e. an experiment wanted to show the side effect of a certain drug on substance abusers in treatment users so the experimenter contacts substance abuse programs and selects people from those.
"n"th Sampling
The experimenter picks every "10"th person or every "2"nd person from a population and that is how your groups are generated.
Systematic sampling v. Random sampling
Research shows the finding are comparable.
Representativeness of the sample
More important to the study than the procedure used to select the population.
Probability samples
Random sampling, Stratified sampling, Cluster sampling, "n"th sampling.
Non-probability samples
Subjects are not selected based on probability. (Judgement sampling, convenience sampling, quota sampling)
Judgement Sampling
Uses the judgement of the experimenter to choose subjects that are thought to be representative of the population
Convenience Sampling
An intact existing group is used with no random sampling
Quota Sample
The subjects have pre-specified characteristics so that your sample will mimic the same type of characteristics that you assume actually exist in the general population being studied.
Hypothesis
The idea or question the researcher wants to answer.
Null Hypothesis
The absence of a relationship between the IV and the DV. No significant difference.
The modern form of describing a hypothesis.
The hypothesis is written in the present tense without the word significant and without any mention of measurement. You might have sub-hypotheses. A null hypothesis might include interaction hypotheses.
Test of significance
Determines what the difference is between the control group and the experimental group. Operate on the principle of probability (p).
Significate findings
p<.05 Only a 5% chance that the difference in the groups occurred by chance.
Confidence or Alpha level
The level of significance.
Alpha Error
Reject Null when it is actually true
Beta Error
Accept Null when it is false
The probability of a type 1 error
The level of significance. If your p value is .05, then .05 is the probability of making a type one error.
Internal validity
Does the experiment demonstrate that the DV changes were caused by the IV, does the treatment make a difference.
External validity
Can the findings of this study be generalized to the general population.
Internal threats to validity
Instrumentation, Maturation, Statistical regression, Attrition.
Instrumentation Threat
When instrument or measurement methods or observers opinion changes impact the experiment
Maturation
Time impacts the results (a person maturing during the study, especially true of developmental studies of children)
Statistical regression
When extreme scores regress to the mean when a test is re-taken.
Attrition or experimenter mortality
When the group does not look the same in the beginning as it did in the end because people dropped out or died. Usually during a longitudinal study. [Show Less]