General Stats and Odds Ratios Flashcards
What are some common types of analysis?
Univariate statistics
Bivariate statistics
Multivariate statistics
What are univariate statistics?
- Frequency
- Mean
- Median
- Mode
- Standard deviation, etc.
What are bivariate statistics?
Relationship between 2 variables. Chi-square, Pearson’s correlation (r), t-test.
What are multivariate statistics?
Relationships among more than 2 variables
What are the four main Scales of Measurement?
NOIR Nominal Ordinal Interval Ratio
What are nominal measurements?
Measures mere differences (ex. hometowns, gender)
What are ordinal measurements?
Measures differences + rank order (ex. place finish in a race; SES [working class, middle class, etc.], religiosity)
What are interval measurements?
Measures differences + rank order + equal distances between values of the variable (ex. IQ - few examples of these non-meaningful zero values)
What are ratio measurements?
Measures differences + rank order + equal distances between values of the variable + true, meaningful zero point (ex. income)
What two Scales of Measurement are categorical/dichotamous?
Nominal, Ordinal
What two Scales of Measurement are continuous?
Interval, Ratio
What is the definition and examples of Nominal?
2 or more categories/groups; measures differences
ex: eye color, city of birth
What is the definition and examples of Ordinal?
2 or more categories/groups with order/rank; measures differences + order
(ex: place finished in a race, SES status)
What is the definition and examples of Interval?
Numerical value measured on a continuum; measures differences + order + equal units of measurement
(ex: temperature, IQ)
What is the definition and examples of Ratio?
Numerical value measured on a continuum; measures differences + order + equal units of measurement + true/absolute zero point
(ex: height, weight)
What things should you keep in mind with Scales of Measurement?
- How we measure phenomena is a choice (ex: race, gender)
- Technically, the statistical test you run depends on: how your variables are measured, your research question
- It is common for researchers to break test & measurement rules
What statistical test is used for nominal vs. nominal measurements?
Chi-squared
What statistical test is used for Nominal (2 groups only) vs. Interval or Ratio?
t-test
What statistical test is used for Nominal (2 or more groups, 1 IV only) vs. Interval or Ratio?
One way analysis of variance (F-test) - ANOVA
What statistical test is used for Nominal (2 or more groups, 2 or more IV) vs. Interval or Ratio?
Factorial design analysis of variance (F-test)
What statistical test is used for Ordinal/Interval/Ratio vs. Ordinal/Interval/Ratio?
Pearson Correlation Coefficient
What is the most common stat you’ll see with categorical outcomes?
Chi-Square test and accompanying p-value
-Categorical = dichotomous outcomes = yes/no values (often as %’s)
What are quantitative outcomes also called?
continuous variables
What is an example of when you’d do a Chi-Square test?
Ex. comparison of the % of men vs % of women who are diagnosed with major depression
Ex. Comparison of freshman, sophomore, junior and senior UMD undergrads earning at least 1 “F” letter grade.
When is a Chi-Square test significant?
When P-value significant data
What does a t-test do?
Another way of comparing values.
- Checking to see if means are significantly different
- T-test designed to compare MEANS - mean values are generally generated for continuous values
What is the Odds Ratio (OR)?
Measure of association between two variables (ex. an IV and a DV)
What is another way of defining OR?
“Odds” that some outcome would occur in the presence of a predictor (IV) vs. absence of the predictor
When are Odds Ratios often discussed within medicine?
Case-control studies
-Though they are approbate for all kinds of categorical data
In many studies we don’t actually know incidence data. What do we use to estimate relative risk in these cases?
Odds Ratio
What does OR = 1 mean?
Exposure does not affect odds of outcome.
What does OR > 1 mean?
Exposure associated with higher odds of outcome.
What does OR
Exposure associated with lower odds of outcome.
What is the equation for OR?
AD/BC
What is A, B, C, and D?
A = Disease +, RF + B = Disease -. RF + C = Disease +, RF- D = Disease -, RF-
