Stats 2 First Exam Flashcards
Descriptive research
Describes population we are studying
Central tendency demonstrates
Mid-points
Spread
Range, SD, D, etc.
Frequency
Number of times it occurs, percent/portion of time it occurs: n, f, p
Inferential research
Infer from the sample to the population
Parameter
Value corresponding to population
Statistic
Value corresponding to sample
Historical research
Looking at past using causal comparative, descriptive, and inferential analysis
Regression
Type of correlation research positing temporal order of variable
Causal-Comparative
Allows for making causal statements
Ex-post facto
Identify settings with differing characteristics and assume difference in results is due to different characteristics
Pre-experimental designs
Are limited. Example: One-shot case study
Quasi-experimental design
Control group and experimental group but no randomization.
True experimental design
Researcher manipulation and randomization
Meta-analyses
Aggregate results from many different studies (frequently based on effect sizes)
Continuous variable
Allows values in-between
Categorical variable
Groups, no in-between
Fixed variable
Allows only certain range (e.g., ages 20-40)
Random variable
Allows all possibilities. Each has equal and independent chance of occurring
Multivariate
More than one DV
Univariate
One DV
Multiple regression
More than one IV
Factorial
More than one IV with analysis of variance
Sampling distribution
Graph statistics of infinite number of samples (graph of means)
Central limit theorem
Graph of means will be equal to population mean (The mean of the means (Samples) is the mean (population mean)
Mean distribution
Unit normal curve
Chi square distribution
Summation of variances
T distribution
Difference between means divided by standard errors
F distribution
Variances compared as ratio
Why is normal curve mother of all curves?
Given an infinite number of samples for any statistic, all will collapse to normal curve
When decreasing alpha,
Beta increases, power decreases
When decreasing beta,
Alpha gets bigger
When increasing alpha
Power increases
How to increase power?
- Bigger sample 2. Stronger tx/effect 3. Improve measurement
Correlational research
Show how y changes when x changes. No causality
Regression
No causality, but do want predictability. Establish equation to predict y. Statistical tool, not type of research– correlation is the type of research. Research question is predictability
Causal Comparative
Attempt to make causal interpretation of the data. Further than relation, further than prediction, this causes the effect.
Wording Cues for Determining Category of Research: Versus
Causal-comparative
Wording Cues for Determining Category of Research: Effectiveness/ effects of
Experimental or causal-comparative
Wording Cues for Determining Category of Research: Positive and negative effects
Experimental or causal-comparative (depending on what was done)
Wording Cues for Determining Category of Research: Relationship
Correlation
One sample tests compare
Sample to population. Does sample match?
Assumption: I
Independence
Assumption: N
Normality of error term (not the sample term)
Assumption: H
Homogeneity - equivalent variances (SD, etc.)
Assumption: R
Randomness of error term
Assumptions of I & R come from…
Methodology and sampling plan
Assumptions H & N…
May be tested
Questions of significance testing
- Is there a difference? 2. Where is it? 3. How big is it/does it matter?
Effect size/strength of association
Percent of variability in DV that can be attributed to variability in IV
What is ANOVA?
Ratio of variability between groups to the variability within groups
SPSS output demonstrating test of homogeneity
Levene’s. Non-significant means assumption of homogeneity upheld.
Use Tukey test if…
- Have found significance. 2. Have = n 3. Are conducting pairwise comparisons
Use Scheffe test if…
- Multiple cells 2. Unequal n pairwise
Helmert contrast
1st vs else
Difference contrast
“reverse Helmert” Last vs. else
What are statistics of strength of association?
- Eta squared 2. Omega squared
Eta squared
- Use with unequal n 2. SSH/SSTotal 3. Is an estimate
Omega squared
- For = n 2. SSB - dfb * MSW (error term) / MSW + SST 3. More precise
f =
MSh / MSe
MSh / MSe =
SSH / dfH / SSE / dfe