Term
What are the two big categories of metrics of data? 

Definition


Term
What are the subcategories of discrete? 

Definition


Term

Definition
cannot be ranked. e.g., religion, political party affiliation, etc. 


Term

Definition
relates information about which cases have similar traits, but allows ranked judgments 


Term

Definition
can be ranked and have equal unit distance across their entire range(e.g. income in dollars each increase by one dollar means the same thing at every point along the range) 


Term
What are two common graphs for categorical variables? 

Definition


Term
What is the only measure of central tendency for categorical variables? 

Definition
The mode the most frequently occurring category 


Term
What are the two major descriptive goals with continuous variables? 

Definition
central tendency, dispersion (spread) 


Term
What are the two broad classes of descriptive statistics? 

Definition
rank statistics, momentbased statistics 


Term
What is the measure of central tendency for rankbased statistics? 

Definition


Term
What is the measure of dispersion for rankbased statistics? 

Definition
The IQR: interquartile range 


Term
What is the measure of central tendency for momentbased statistics? 

Definition


Term
Which type of data, rank or momentbased, is more sensitive to outliers? 

Definition
Momentbased, because the mean only needs a little bit of an outlier to be thrown off, while the median doesn't break down with outliers 


Term
What are the measures of spread for momentbased statistics? 

Definition
The variance and the standard deviation 


Term
What would happen to the variance if we had no variation in y at all? 

Definition
Variance would equal zero no spread around the mean. 


Term
What happens to the variance as data are spread further from the mean? 

Definition


Term
What is the standard deviation? 

Definition
the average dierence between values of y and the mean of y 


Term
What are the two key dimensions of dependent variables? 

Definition


Term
What are two types of research designs (hint: think spatial and temporal) 

Definition
Crosssectional, time series 


Term
What is crosssectional data design? 

Definition
Looks at multiple units at one time 


Term
What is temporal data design? 

Definition
Looks at one unit over time 


Term
Why might causality be clearer in a time series? 

Definition
we can examine a phenomenon before and after some independent variable changes 


Term
What kind of causal theories are common with the physical sciences? 

Definition
Deterministic theories: an increase in X by a certain amount will *always* cause an increase in Y of a certain amount 


Term
What kind of causal theories are more common with humans? 

Definition
Probabilistic: Increases in X cause increases in Y on average 


Term
What is an ecological fallacy? 

Definition
inferring individual behavior from population averages 


Term
What is the first hurdle? 

Definition
Is there something connecting x and y does it make sense that they might cause one another in a traceable way? 


Term
What is the second hurdle? 

Definition


Term
What is the third hurdle? 

Definition


Term
What is the fourth hurdle? 

Definition
Can we eliminate any Z's that might relate to X and Y and cause Y ? 


Term
Finish this phrase: "While correlation does not mean causation," 

Definition
Correlation is necessary for causation to exist. 


Term

Definition
a research design in which the researcher both controls and randomly assigns values of the treatment (key independent variable) to participants 


Term
What are the two key components of experiments? 

Definition
control, random assignment 


Term

Definition
The value(s) of the treatment (key independent variable) X are determined by the researcher and not by the participants or nature. 


Term
What two groups comprise the experimental group? 

Definition
Treatment group, control group 


Term
What does randomization control for? 

Definition
for every possible Z regardless of whether we can even list the possible Zs 


Term
Experiments have good ____________ validity but bad ____________ validity. 

Definition


Term
What is internal validity? 

Definition
The extent to which we can accurately state that the observed independent variable produced the observed effect 


Term

Definition
relates to the generalizability of your findings 


Term
What can help with the idea that experiments are low on external validity? 

Definition


Term
What is an observational study? 

Definition
one in which the researcher does not have control over the quantities of the independent variable (or any variable) 


Term
What is the population of interest in an experiment? 

Definition
the set of units (people, countries, etc. . . ) that the researcher's theory relates to 


Term
What are the two ways to get observational data? 

Definition
Measure the entire population of interest, measure a sample of the population of interest 


Term
What are the two types of data in an experiment? 

Definition
Population data, sample data 


Term
What is population data in an experiment? 

Definition
data about every possible relevant case 


Term
What is sample data in an experiment? 

Definition
a dataset drawn from a subset of cases of some underlying population 


Term

Definition
Dened by the characteristic that every member of the population of interest has an equal probability of being selected for participation in the study. 


Term
What is a convenience sample? 

Definition
Use participants that are readily at hand 


Term
What is the difference between random assignment and random sampling? 

Definition
Random assignment refers to the decision about whom to give a potential treatment. We randomly assign people to the treatment group from the larger experimental group.
Random sampling refers to drawing at random of a sample to study. Usually done (or attempted) in survey research. 


Term
Without experimental control and random assignment, crossing hurdles ___ and ___ of causal evaluation is difficult. 

Definition


Term
What kind of test do you perform if both variables are categorical? 

Definition


Term
What kind of test do you perform if both variables are continuous? 

Definition
Correlation coefficient (Pearson's r) 


Term
What kind of test do you perform if the dependent variable is continuous and the independent variable is categorical? 

Definition


Term
What kind of test do you perform if the dependent variable is categorical and the independent variable is continuous? 

Definition


Term
What do p values range between? 

Definition


Term
What does the p value show? 

Definition
the probability of randomly finding a relationship in the sample that does not exist in the population 


Term
As the p value approaches ____ we get more confidence that there is a real relationship between the two variables in the population 

Definition


Term
The more data we have, the _____ our p values will be. 

Definition


Term
If a p value is less than ____, the relationship is said to be _______ ________. 

Definition
0.05, statistically significant 


Term
What are the three steps to trying to interpret cross tabs? 

Definition
1. Figure out what defines the rows and columns 2. Figure out what each cell tells you 3. Look for general patterns 


Term
When is Pearson's chi squared (x^2) statistic used? Write it down. 

Definition
Used to find the relationship between two categorical variables. 


Term
How do you calculate the degrees of freedom for the chisquared statistic? 

Definition
df = (r  1)(c  1) where r is the number of rows in your table and c is the number of columns 


Term
When do you use a ttest? Write down the formula. 

Definition
When the dependent variable is continuous and the independent variable is discrete. 


Term
What does the numerator of the ttest formula tell you? 

Definition
the greater the dierence between the means, the higher the value of t will be 


Term
The denominator of the t test requires the _____ ______ of the difference of the two means. Write down how this is calculated 

Definition


Term
How do you calculate degrees of freedom for the ttest? 

Definition
Subtract one from the smaller of the two n's 


Term
When do you use Pearson's r (correlation coefficient?) 

Definition
When both the independent and dependent variables are continuous 


Term
What does covariance mean? 

Definition
That the variables change together 


Term
How do you calculate the covariance between two variables? Write it down. 

Definition


Term
If ___ is systematically higher than its mean for the same observations in which ___ is higher than its mean, we'll get a ________ contribution to the covariance. 

Definition


Term
How is Pearson's r calculated? Write it down. 

Definition


Term
What tstatistic is used to determine whether two continuous variables have a higher correlation than we would expect at random? Write it down. How are degrees of freedom calculated? 

Definition

