Final Flashcards
MCD is a mathematical multiple of ___
SEM
______ often used to construct and evaluate scales/questionnaires
Internal consistency
Logistic =
Use of categorical variables
DV is categorical
Ex: success vs non-success
Which correlation coefficient?
1 ordinal and 1 ratio/interval
Spearman’s rho
Kappa interpretation
Basically same as ICC
Depends on weights used;
Exactly same as ICC when weights squared
< 0.4 poor-fair
- 4-0.6 moderate
- 6-0.8 substantial
- 8-1.0 excellent
1-way ANOVA
Parametric
3 or more independent groups
1 IV with 3 or more levels
Logistic regression
Trying to predict a dichotomous variable
Diagnosis (have vs doesn’t have condition)
Outcome of treatment (success vs non-success)
Assumptions of regression analysis
Linear relationship = approximation of “true” lone in population
For every X there is a normal distribution of Y (sample data include random samplings from these distributions in Y)
Homogeneity of variance
DV = continuous measure
Discrete (nominal/ordinal) reliability coefficients
Percent agreement
Kappa - better
Regression is a __ statistic
Linear relationship =
Parametric
Linear relationship = approximation of “true” line in population
For every X there is a normal distribution of Y (sample data includes random samplings)
Homogeneity of variance
Logistic regressions primary outcome ____
OR (odds ratio)
Null value is 1 (not 0)
Which correlation coefficient?
All nominal dichotomy
Phi coefficient
Linear =
Use of continuous variables
DV is continuous
Ex: does age predict BP
Which correlation coefficient?
1 nominal dichotomy, 1 ratio/interval
Point biserial
Interpretation of Relative Risk and Odds Ratio scores
RR or OR = 1
Null value
No association between exposure and disease
RR or OR > 1
Positive association
Exposure considered harmful
RR or OR < 1
Negative association
Exposure is protective
Kruskal–Wallis ANOVA
Dependent variable Ordinal
Can not assume normal distribution
3 or more independent groups
1 IV with 3 or more levels
Coefficient of determination
Square of correlation coefficient
Done bc more directly interpretable
“The % of variance in y that is explained - or accounted for- by x”
Reliability is tied to the concept of
Measurement error
ICC estimate based on ___ will always be substantially higher than estimate based on ____
Average measures always high than single measures
ANOVA of regression
Test hypothesis that predictive relationship occurred by chance
If b (slope) = 0, line is horizontal = no relationship
If p < than alpha, reject null and conclude predictive relationship is significant
Paired t-tests
Parametric
1 group
1 IV with 2 levels
ICC interpretation showing “good reliability”
ICC > 0.75
ICC Model 1
Each subject measured by different set of raters; randomly chosen
Rarely used in clinical research
A reliable measure can be expected to
Repeat the same score on 2 different occasions provided that the characteristic of interest does not change
Interpretation of correlation coefficients
- 00-0.25 = little to no relationship
- 26-0.50 = fair relationship
- 51-0.75 = moderate to good
- 76-1.00 = good to excellent
These values are NOT strict cutoff points. Depends on type of research.
Most predictors are ___ scale, but can also use ___. But not ____.
Most predictors are continuous scale
Can also be dichotomous or ordinal scale
But NOT multi category nominal (ie race)
ANOVA
Umber of IV and DV
IV : more than 1
DV: 1
Rxx (reliability coefficient) will be bigger when
True variance is larger
Nonparametric tests are ___% of parametric tests with regard to power
65-95% as powerful as parametric equivalent
Reliability coefficient (rxx) ranges ___ meaning
Range 0-1
0 = no reliability
1 = perfect reliability
Multiple linear regression
More than 1 predictor in the model
Y= a + b1X1 + b2X2 a = regression constant b1X1 = 1st regression coefficient x 1st predictor B2X2 = 2nd regression coefficient x 2nd predictor
Note- there can be more than 2
Hierarchical Linear Modeling (HLM)
Linear mixed modeling
For use when data is “nested” within groups
(Students nestled within classroom,
Patients nested within clinics)
Occasions nested within subjects
Treats each subject like a regression line
Analyzes “trajectory” of each subject in each group
Standardized Beta Weights
Helpful to know relative contribution of each predictor variable
Impossible to tell with raw regression coefficients (ie b1 May be in years, b2 lbs.)
Raw coefficients transformed into unitless beta weights
Accuracy of prediction
Correlations only applicable for ___ of scores. Correlations quantify strength of ____ only.
Pairs of scores
Linear relationships only - based on equation for a straight line.
MANOVA
Number of IV and DV
IV = more than 1
DV = more than 1
MANOVA is for analyzing >1 DV simultaneously
Nonparametric stats are based on…
Comparisons of ranks of scores
Comparisons of counts (yes/no) or “signs” of scores
Phi coefficient
Both variables dichotomous
Ex: gender and group
Worthless scatter plot
Does NOT work with non-dichotomous nominal
Similar to chi-square test (will give same p-value)
But phi gives strength of relationship
Both ____ and ___ give single indicators of reliability that capture strength of a relationship plus agreement in a single value
ICC and Kappa
Problem with correlation coefficient (Pearson’s r)
Assess relationship, not agreement
Only 2 raters or occasions can be compared
___ gives “unstandardized” estimate of reliability (ie untis of measurement)
SEM
Cronbach’s alpha represents correlation ____
Among items and correlation of each individual item with the total score
Spearman Rank (rho) correlation coefficient (rs)
Nonparametric analog of Pearson’s r
1 continuous, 1 ordinal variable OR 2 ordinal variables
Analysis of residuals to test assumptions
Plot residuals on ___-axis
Predicted values on ___-axis
Residuals on y-axis
Predicted values on x-axis
Looking for symmetry
The amount of change in a variable that must be achieved to reflect a true change/difference
MDC minimal detectable difference/change
Point biserial correlation (r pb)
1 variable dichotomous, 1 variable continuous
Does NOT work with non-dichotomous nominal (ie age and race)
Computationally same as Pearson’s r
Results same as t-test
Ex: gender vs height
CV is unit-less, so helpful comparing ____
Variability between 2 distributions on different scales
Logistic regression
DV=
Predictors =
DV = dichotomous
Predictors (IV) = continuous, ordinal or dichotomous
We use __ to predict ___ In linear regression
X (IV) to predict Y (DV)
3 types of stepwise procedures
Forward: start with no predictors, then add
Backward: start with all predictors, then remove
Stepwise: start with no predictors, then add but can also remove
___ is stability of repeated measures over time. Is basically the same as test-retest reliability
Response stability
Kappa can be used on __ data
Nominal and ordinal
Adjusted R^2
Chance corrected R^2
Adjusted down for having more predictor variables
Accuracy of prediction
The % of variance in y that is explained (or accounted for) by x
Coefficient of determination
Multicolinearity
When Xs in model are substantially correlated with each other
Creates problems with interpretations of b weights
Select independent predictors: not highly correlated w/ each other but highly correlated w/ dependent (predicted) value
Non-parametric:
IV Level of measurement
DV level of measurement
Question
IV: nominal
DV: ordinal
Q: ranks different?