Stats Unit test

What measure of spread and measure on center are NOT affected by outliers?

Median and IQR

Define inferential statistics

-consists of generalizing from samples to populations, performing estimations and hypothesis tests, determining relationships among variables, and making predictions. - The statistician tries to make inferences using probability like in the insurance industry. -Relationships

descriptive statistics

-consists of the collection, organization, summarization, and presentation of data. -The statistician tries to describe a situation like in the national census. -Averages

NO QUESTION, JUST A HELPFUL LISTING

1. Nominal - categorical (names) 2. Ordinal - nominal, plus can be ranked (order) 3. Interval - ordinal, plus intervals are consistent 4. Ratio - interval, plus ratios are consistent, true zero

Name the three percentages for the first thee standard deviations.

68%-95%-99.7%

What is a cofounding variable?

A factor other than the independent variable that might produce an effect in an experiment. Example: House fires increase as snow increases. So snow must set houses on fire. In reality, people using a fireplace more because of the cold would be the cofounding variable.

List four requirements of a frequency distribution.

Between 5-20 classes, no gaps, no overlaps, and consistent class widths,

Define ordinal

Classifies data into categories. Ranking, but no precise differences between rankings exist.

Define nominal

Classifies data into mutually exclusive nonoverlapping exhaustive categories.

In this type of sample, the population is divided into groups, then some of the groups are randomly selected for surveying. Ex: Frontier airlines wants to survey its costumers. They randomly select 5 flights and survey the passengers on those flights.

Cluster sample

In this type of sample, the researcher uses samples that are readily available to them in a non-random way. Ex: surveying everyone leaving gym class.

Convenience sample

Difference between discrete and continuous data. Give examples.

Discrete data is counted, ex: numbers on a dice, number of students, number of cars. Continuous data is measured, ex: Temperatures, lengths, heights, times.

In this type of study, investigators apply treatments to people, cats, plants, etc. and observe the effects of the treatments.

Experimental

Define quasi-experimental

If random assignment is not possible, researchers use intact groups. The treatments are assigned at random, but whole groups are used (classrooms, etc...)

Temperate and IQ score are examples of this level of measurement (NOIR)

Interval

Gender, zip codes, political affiliation, religion, and marital status are examples of this level of measurement (NOIR)

Nominal

In this type of study, the person collecting data has no control over the information/happenings of what they are studying.

Observational

Letter grade, judging contest, ratings (average, poor), and sizes like small medium and large are examples of this level of measurement.

Ordinal

Give the two equations to find any outliers

Q1-1.5(IQR) and Q3+1.5(IQR)

Difference between qualitative and quantitative data. Give examples.

Qualitative, or categorical data: has no measurable differences, can not be logically ordered. Ex:1st, 2nd, 3rd place, Ice cream flavors Quantitative data: Numbers can be ranked or ordered. Ex: Heights weights, age, body temp

Define Interval

Ranks data between units of measure do not exist. No meaningful zero.

Height, weight, area, number of phone calls received, and salary are examples of this level of measurement (NOIR)

Ratio

In this type of sample, the population is split into groups, and a few members from each group are randomly selected. Ex: Three students are randomly selected from each classroom to vote on the lunch menu.

Stratified sample

In this type of sample, a population is put into an order, and every nth number is surveyed. Ex: Every 5th person in my contact list takes a survey.

Systematic sample

To find the skew of a histogram, do you look at the tail or the highest part of graph?

Tail

Define variable

a characteristic or attribute that can assume different values.

Define data set

a collection of data values.

Define sample

a group of subjects selected from a population.

Define population

consists of all subjects (human or otherwise) that are being studied.

X subscript m represents

midpoint

n represents

number of values in a set

Define cofounding variable

one that influences the dependent variable but was not separated from the independent variable.

Define ratio

precise differences exist, true zero exists

Define parameter

refers to data in a population. These will be Greek letters.

Define statistic

refers to data in a sample. These will be Roman letters ( x, s, a, b)

s represents

standard deviation

What is the Hawthorne effect?

subjects participating in an experiment may change their behavior in ways that affect the results of the study.

Ex represents

sum of x's

Define statistics

the science of conducting studies to collect, organize, summarize, analyze, and draw conclusions from data.

Define data

the values (measurements or observations) that variables can assume.

The mean, median, and mode are the same in a __________ distribution.

unimodal, symmetrical

Define random variables

variables whose values are determined by chance.

s^2 represents

variance

How do you write an equation of least squares regression line?

y^1=intercept + X Variable 1(X) Example: y^1=102.9-3.6x