1 Flashcards
TERM: Sample of convenience?
Collection of individuals that happen to be available at the time.
Variable?
Characteristic measured on individuals drawn from a population under study.
Data?
Collection of values from 1 or more variables made on a collection on individuals.
How do a predict a response variable?
From an explanatory variable.
Populations <-> _____, samples <-> ______ ? 2•
•Parameters, •Estimates
Biased sample?
A sample size whose individuals picked are not picked at equal probabilities because a characteristic may be biased.
If estimates tend to differ from the parameter, then the estimate is?
Biased.
Accuracy (unbiased)?
On average gets the correct answer.
Precision?
Gives a similar answer repeatedly.
Properties of a good sample? (3•)
•Large sample size
•Each individual has equal probability of being selected (unbiased)
•Independent selection of individuals
In a random sample ____?
Each member of a population has an equal and independent probability of being selected.
Estimates are ________ changing from one random sample to another sample.
Random variables
Sampling error?
Chance difference between an estimate and population parameter being estimated (sampling bias not included).
Error?
Random difference between estimate and true population.
What increases the probability of having a higher accuracy and precision?
A larger sample size.
!!!Categorical variables:
ordinal,
nominal,
numerical variables?
•Fits into a category
•a variable that has an order to it (numbers are ordered)
•
•Just a number
Cumulative frequency distribution?
Proportion of individuals equal to or less than that value.
explanatory vs response variable? (2•)
•Explanatory variable is the action to find the solution of an experiment while the •response variable is the solution of the experiment.
Numerical data uses what methods?
Histogram
Cumulative frequency
Distribution
Categorical data uses what methods?
Bar graph
!!!Two common descriptions of data
Means in a sample are often notated as?
n bar.
mu =?
Mean of population.
!!!!!In statistics, we use n,N for sample size and n,N for population? (2•)
n, N
Median?
Middle measurement of a set.
Mode?
Most frequent measurement (NOT THE MOST OF THE RESPONSE VARIABLE)
