Mock exam Flashcards
Part-worth utility
–> used to calculate the total utility vakue per each object and the relative importance of the attributes
- accord. to the the empirically determined ranking of the stimuli
- for all attributes of each variable
Importance
= Difference between the highest and the lowest par-worth utility of the attribute values
Cluster combined
which clusters are combined to a new cluster in the respective step
Cluster analysis - Coefficients
showes the euclididan distance measure - the values correspond to the error sum of squares if ward’s method is used
what if coefficients increase?
A large increase is an indicator for a reasonable cluster solution
stage cluster first appears / next stage
shows in which steps clusters are merged to already existing clusters
Reasons for insignificant explanatory variables in a regression mdoel?
What effects does insignificance have?
What actions have to be taken in order to solve insignificance
- no correlation with the dependent variable / or no other variable takes care of it
- you dont need to do anything
R² goes … with every added variable
goes up
How do multicollinearity, omitted variable bias, and endogeneity correlate?
Multicollinearity: highly correlated explanatory variables
–>increase sample size, eliminate variable but lose info, leave it as it is, aggregate into factors
Omitted variable bias: Problem of multiple regression; causes high SE, RE is unbiased, but inefficient –> use robust estimates
endogeneity: explanatory variabl is corrletaed with the error term, caused by omitted variables, autoregression and measurement errors
Z-test
T-test
Differences?
T-test:
One: compare sample means with pop mean
H0: b =0
Two: compare (in)dependent samples
- use for N < 30
- follows Students T-distribution
- unknown SD!
Z-test:
compare sample & pop means
- use for N > 30
- normally distributed (for large N a t-test becomse similar to a z-test)
- known SD!
Right-skewed:
gm median and mean
left skewed:
gm median and mean
right:
gm > 0
median < 0 and < mean
left:
gm < 0
median > 0 and > mean
whats the p-value?
The probability of obtaining the observed value, or even larger ones, if H0 was true
advantage of spearmans rho over bravais pearson ?
it decreases the effect of outliers
conceptualization
measuring of a concept that is not directly observable
basic idea log regr
log. regression determines the probability of a certai result & analysis which factors infuence this probability
DV: dummy