Module 4 Flashcards
Variables and Descriptives
What are statistics?
A subfield of math useful for collecting, analyzing, interpreting, and presenting data
What is the MAIN purpose of statistics?
Description and inference
What is description in relation to statistics?
Using statistics to describe and summarize a set of data
What is inference in relation to statistics?
Using statistics to infer from a sample to a population
What are the three sub-purposes of statistics?
- Describing data
- Describing relationships among variables
- Identifying differences among/between groups
How can you classify variables in statistics?
- Independent/dependant variables
- Level of management
What are the four levels of measurement in statistics?
- Nominal
- Ordinal
- Interval
- Ratio
What are nominal variables? Give examples.
Non-numerical measures are labeled by a name or category
Ex: Sex and Year in School
Explain the rules of nominal variables.
- You cannot say one variable is better than the other
- Nominal variables will be used like independent variables (but we are not manipulating them)
What are ordinal variables? Give examples.
Non-numerical measures that are labeled by a name and placed in a specific order
Ex: Likert Scale ( A, SA, N, SD, D )
What are interval variables? Give examples.
Variables that have equal intervals between points, but there is no true zero.
Ex: Temperature, Knowledge
What are ratio variables? Give examples.
Variables that have equal intervals between points, but there is a true zero.
Ex: Body Weight, Money
What are descriptive statistics?
Statistics that describe your data
What are the two common measures of descriptive statistics?
- Central Tendency
- Variability
What is central tendency?
When data clusters around a single point
What is variability?
When data is spread out
What are the measures of central tendency?
Mean, median, and mode
What are the measures of variability?
Range and standard deviation
What is range?
The difference between the highest and lowest scores in the data set
What is standard deviation?
The estimate of the spread of scores around the mean
True or False?
You can report the mean alone.
False, you must ALWAYS report the standard deviation with a mean.
What is a normal curve?
A theoretical distribution of scores to help understand standard deviation
What are the characteristics of a normal curve?
- Symmetrical
- The mean, median, and mode are equal
- You can make probability statements
What are the probability statements you can make about a normal curve?
- 68% = 1 SD of mean
- 95% = 2 SD of mean
- 99% = 3 SD of mean
What is skewness?
An indication of the direction of the tail of the curve
What is a positive skew?
The tail of the curve goes to the right
What is a negative skew?
The tail of the skew goes to the left
What is kurtosis?
Indication of the shape of the curve
What are leptokurtic distributions?
- Positive kurtosis
- More peaked and skinny
What are platykurtic distributions?
- Negative kurtosis
- Less peaked and wide
