Week 11 Flashcards
(49 cards)
What is a z-test
Hypothesis test used for a single mean if the sample is large enough and drawn at random
How do you find the z-test
- Specify the null and alternative hypothesis
- Specify the level of sampling error allowed
- Determine the sample standard deviation
- Calculate the estimated standard error of the mean using the formula
- State the result whether the null hypothesis can be rejected
What is a t-test
Hypothesis test used for a single mean if the sample is too small to use the z-test
How to do the t-test
- Specify the null and alternative hypothesis
- Specify the level of sampling error allowed
- Determine the sd
- Calculate the standard error
- Calculate the t-statistic
- State the result
How do you hypothesize about two means
- Specify the null and alternative hypothesis
- Set the level of sampling error
- Calculate the estimated standard error of the differences between the two means
- Calculate the test statistic Z
- State the result
What is an experiment
Research approach where one variable is manipulated and the effect on another variable is observed
What is experimental research referred to as
Causal research because it is the only type of research that has potential to demonstrate change in one variable
What are three things you must show in an experiment
- Correlation or concomitant variation
- Appropriate time order of occurencce
- Elimination of other possible factor
What are three types of evidence for causal relationships
- Correlation
- Appropriate time order of occurrence
- elimination of other possible causal factors
What are ways to show a causal relationship
- Correlation between two variables
- Showing that there is an appropriate time order of occurrence
- Eliminating other possible causal factors
What are laboratory experiments
Experiments conducted in a controlled setting
What are field experiments
Tests conducted outside the lab in an actual environment
What is validity
Defined as the degree to which an experiment actually measures what researchers was trying to measure
What is internal validity
Refers to the extent to which competing explanations for the experimental results observed can be ruled out
What is external validity
Refers to the extent to which the causal relationships measured in an experiment can be generalize to outside persons, setting and times
What is experimental notation
- X is used to indicate the exposure of an individual or a group to an experimental treatment
- O is used to refer to the process of taking measurements on the test units
- Different time periods are represented by horizontal arrangements
What are test units
Test units are individuals, groups of individuals or entities whose response to the experimental treatments is being tested
What are extraneous variables
Variables that pose a threat to experimental validity
What are some examples of extraneous variables
- History
- Maturation
- Instrument variation
- Selection bias
- Mortality
- Testing effects
- Regression to the mean
History
This is the intervention between the beginning and end of the experiment of any variable or event other than those manipulated by the researchers
Maturation
Refers to changes in subjects during the course of the experiment that are a function of time; it includes getting older, hungrier more, the like
Instrument variation
Refers to any changes in measurement instruments that might explain differences in the measurement taken
Selection bias
Is encountered in situations where the experimental or test group is systematically different from the population to which the researcher would like to project the experimental results or from the control group
What do researchers do to ensure equality of groups?
- Randomization involves assigning subjects to test groups and control groups at random
- Matching involves what the name suggests making sure that there is one to one match between people or other units in the test and control groups in regard to key characteristics
