Vocab & Variables
This term means the set of procedures used to organize, summarize, and communicate numerical information.
What is statistics?
Categories that are labels only, with no ranking.
What is nominal?
The only measure of central tendency usable with nominal data.
What is the mode?
The shape of the normal distribution.
What is bell-shaped (and symmetrical)?
A number describing a population (vs. a statistic, which describes a sample).
What is a parameter?
In "Does education predict income?", income plays this role.
What is the dependent variable (DV)?
The level with a rank order but unequal gaps between categories.
What is ordinal?
For 4, 6, 8, 10, 12, this is the mean.
What is 8?
The approximate percentage of cases within ±1 standard deviation of the mean.
What is 68%?
σ/√N gives this quantity.
What is the standard error (of the mean)?
A variable with only two possible values is called this.
What is a dichotomous variable?
"Number of children" is this level AND this subtype (whole numbers only).
What is interval-ratio, discrete?
When the mean is greater than the median, the distribution has this shape.
What is positively skewed?
The formula Z = (Y − Ȳ)/s produces this.
What is a Z score?
This theorem says the sampling distribution is ~normal when N ≥ 30.
What is the Central Limit Theorem?
A measure that is consistent has this property; a measure that is accurate has this one.
What are reliability and validity?
This property means you can downgrade a variable's level but never upgrade it.
What is the cumulative property?
This measure of spread equals the square root of the variance.
What is the standard deviation?
For a mean of 100 and SD of 20, a score of 140 has this Z score.
What is 2.0?
The Z value used to build a 95% confidence interval.
What is 1.96?
These are the three conditions required to establish causality.
What are time order, a real relationship, and no other explanation?
The only math appropriate for a nominal variable.
What is counting cases in each category?
Q3 minus Q1 gives this measure, capturing the middle 50%
What is the interquartile range (IQR)?
The mean and standard deviation of the standard normal distribution.
What are 0 and 1?
When two groups' confidence intervals do this, the difference is considered real.
What is not overlap?