final quiz rm ch 9, 10, and 12 Flashcards
Reviewing three Casual Claims
Covariance
Temporal Precedence
Internal Validity
multivariate designs
longitudinal designs help address temporal precedence
multiple regression analyses help address internal validity
Longitudinal designs
measure the same variable in the same group of people at different times
cross sectional
two variables measured at the same point in time are correlated
cross-lag correlations
the earlier measure of one variable is associated with a later measure of another variable (looking at how people change over time) – help us establish temporal precedence
Regression results indicate whether a third variable explains the relationship
Criterion variables and predictor variables
- Using beta to test for third variables
- Predictor is independent variable
- In a multiple regression analysis, you will be studying three or more variables – you choose the variable you want to understand and that is called your criterion or dependent variable
- Where you see multiple regression output you will see a beta – in this example you will have one beta for exposure to sex on tv and another beta for age
- R just shares that there is a relationship between variables
- There is a negative relationship between the predictor variable and the criterion variable when other variables are constant
- No relationship when other predictors are controlled for
Smaller the beta the weaker the relationship and the bigger the beta the stronger the relationship (B will be what you see in graphs) – B is unstandardized coefficient and beta is standardized coefficient
B is just like beta and we think about the positives and negatives in the same way
o We can not compare two B values in the same table
o But we can compare two beta values in the same table since one is standardized and one is unstandardized
o When we think about B – unstandardized, Beta = standardized
o Beta and B tell us information similar to what R tells us
criterion
dependent
Using Beta to test for third variables continued
95% Cis and statistical significance of Beta
- Your P value of .05 is complementing your .95 from CI
- When the P is greater than .05 the associated CI does include zero
- When the P value is less than .05 the associated CI does not include zero
Higher beta, smaller beta
stronger relationship, weaker relationship
Betas are
helping us answer our research questions and is a standardized coefficient that we can compare in one table – we can’t compare beta’s between two different tables
regression in pop media articles
Controlled for
- Adjusting for
- Considering
Regression does not establish causation
Multiple regression – is not foolproof way to rule out all kinds of third variables
- We can’t control variables we don’t measure
- There could be some variables we didn’t think about measuring
Mediators versus third variables
Similarities
Both involve multivariate designs
Both can be detected using multiple regression
Differences
Third variables are external to the bivariate correlation (problematic)
Mediators are internal to the causal variable (not problematic).
Mediators versus moderators
Mediator- Why?
Moderator- For whom and when does this relationship exist?
Covariance
it’s about the results and differences between groups
Control groups, treatment groups, and comparison groups
Control group- no treatment condition (not a control variable). This condition has no treatment and compare it to one with a treatment
Treatment group- One or more treatment conditions
Placebo group- control group exposed to a treatment that is inert
Well-designed experiments establish internal validity
Design confounds- When a second variable varies systematically along with the independent variable and it gives us an alternative explanation for our results. Unable to support a causal claim. Only threatened if there is systematic variability which can’t be controlled
Ex: Students in the laptop group answer more difficult questions than the long-hand group. Can’t tell the cause because of a difference in the dependent variable
Selection effects- When the participants in one level of the IV are systematically different than the participants in another level of the IV
Random assignment avoids selection effects
Matched groups avoid selection effects. Ex: Matching IQ
Independent-groups design (between-subjects designs)
Different groups of participants that are placed at different levels of your IV
Posttest only
Equivalent groups. Simplest type of independent groups experiment where participants are randomly assigned to IV groups and are tested on your DV one time
Pre-test Post-test design
Participants are randomly to at least two different groups and are tested on the key DV twice (before and after)
Within-groups design
Each participant is presented with all levels of the IV
Repeated-measures design: Participants measured on the dependent variable more than one time after exposure to each level of the independent variable
Ex: Group tastes chocolate with confederate and say it tastes better than trying the same chocolate alone
Concurrent-measures Design- All participants are exposed to all levels of the independent variable are roughly the same time
Advantages of within-groups design
Participants in your groups are equivalent because they are the same participants and serve as their own controls
Within-groups designs require fewer participants than other designs.
Order effects:
When exposure to one level of the independent variable influences reactions to other levels of the independent variable. Applies to any design
Practice effect: When our participants are either getting better or worse at a task from practice or fatigue. (also known as fatigue effect)
Carryover effect: When one condition carries over to the next
Avoiding order effects
Two types of counterbalancing
Presenting the levels of independent variables in different orders
Full counterbalancing: all possible condition orders are presented
Partial counterbalancing; Only some of the possible condition orders are used
What a mediating variable it is, what question your mediator asks?
Think about regression analysis, or what it means when you add extra variables to your regression analysis.
all coefficients are changed
Be able to understand what a matched group design is
What are things you lok for in multiple regression analysis? What values?
Coefficient estimate for the regression. Tell us what the correlation coeffeicei
This particular variables significantly predicted above and beyond all of the other variables there
Or does not
TYPES OF BETA VALUES:
Standardized betas: compare the values in the tables compare values with all the IV. Cannot compare standardized betas with other standardized betas in other tables Two different tables
Unstandardized betas: we know the relationship between the DV and IV but you can not compare these in a table. You can not compare those.
Standardized betas
compare the values in the tables compare values with all the IV. Cannot compare standardized betas with other standardized betas in other tables Two different tables
Unstandardized betas
we know the relationship between the DV and IV but you can not compare these in a table. You can not compare those. tell us if the IV is a significant predictor of the dependent variable