Unit 2: Data, Sample, Variables Flashcards
Research Design
formal plan for gathering and analyzing data
Independent variables (IV)
Antecedent variables and affect other variables
* Aka, “X” variable, predictor variable
- Dependent variables (DV)
- Affected by IVs
- Aka, “Y” variable, outcome variable
Measurement scales
Types of Statistics
- Descriptive
- Inferential
Descriptive Statistics
Summarize the characteristics of a data set
Inferential Statistics
Analyze the larger group (i.e., population) through the smaller group’s (i.e., sample) characteristics to draw inferences about the population
give an example of inferential statistics
Examples:
* How does a good kindergarten classroom affect children’s life outcome?
* Do students of the same aptitude perform the same on all test questions? Are some
questions more difficult for certain groups of students?
give an example of descriptive statistics
- SAT test scores for the incoming students
- What is the average?
- What is the composite SAT scores of Bio 93 students?
Population
all members of a defined group
Population includes all individuals or objects of interest
μ (“mu”)
represents mean of some characteristic in a population
* Example: Coffee consumption of Americans (American population =
329.5 million in 2020)
* Mean of coffee consumption, μ = 3 cups a da
Sample
any subset of a population
Sample is all cases that we have collected data on (a subset of the population)
Example: random sample of 1,000 college students
* Mean of coffee consumption, M = 4 cups a day
M
mean of a sample
Statistical inference
is the process of using data from a sample to gain
info about the population