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Universities » University of California - Irvin.. » Stats - Statistics » 7 - BASIC STATISTICS » Flash Cards

MT 1 - Flashcards

Flashcard Deck Information

Class:	Stats 7 - BASIC STATISTICS
Subject:	Statistics
University:	University of California - Irvine
Term:	Spring 2010

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Regression Line

Straight line that describes how a response variable y changes an explanitory variable x changes

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slope of a regression line

y(hat) = a + b(x)

rate at which the predicted response y(hat) changes along the line as the explanitory variable x changes.

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Observational Study

observes individuals and measures variables of interest but does not attempt to influence the responses. The purpose of an observational study os to describe some group or situation.

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Experiment

deliberately imposes some treatment on individuals in order to observe their respponses. The purpose of an experiment is to study whether the treatment causes a change in the response.

When the goal is understanding cause and effect, experiments are the only source of fully convincing data.

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Confounding Variables

Two variables (explanitory or lurking variables) are confounded when their effects on a response variable cannot be distinguished from eachother.

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Methods of Comparison

Statisticians use the methos of comparison when they want to know whether...

A new vaccine will lower the rate of influenza

Psychological environment affeccts brain anatomy

educational standards affect test scores

Vitamin C prevents or shortens colds

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Treatment Vs. Control

Treatment: Group actually being treated

Control: Group recieving a placebo

Used in experiments

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Randomization

1. Minimizes the bias - compare Salk Field Trial with NIFP

2. Calculate chance

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Methods of Comparison

Exposed vs. unexposed

Experiments:
-Key Variables are held constant
-Control over group assignment, where...
-Impartial chance, called randomization, works best
-Treatments are interventions, where...
-The goal is a description of the effect.

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Observational Studies

-No control over group assignment, often self selection or exposure by association

-observations, not interventions

-Key variables may vary, so...confounding is always a risk

-Matching, strategic, but not always effective.

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What is significant about self selection for experiments?

Confounding: not as random

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Confounding variables

observational studies associate with smoking but correlates with alcohol - correlates with exposure and outcome an dgets mixed up

-Lurking variable

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What kind of experiment was the Clofibrate Trial?

some people were adherers, some were non

semi-observational study

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What does a histogram measure?

-Demographic variables, like age, education, and income;

-Psychological variables like height, weight, blood pressure, and serum cholestorol levels;

-Dietary habbits;

-Prevalence of diseases, like diabetes or obesity.

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Bar graphs show what kind of data

-Demographic variables like age, sex, race;

-Employment status like employed, unemployed, or outside the labor force;

-Incomes like annual wage, salary, wage rates, or other sources.

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Qualitative Variables

Variables which classify subjects into two or more categories or nominal groups...
-Sex, race, employment, disease type

-Bar charts

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Quantitative Variables

Variables which measure characters of subjects on numerical scales with a well defined measure.

-blood pressure, weight, annual income, age, etc

-Histograms

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How do you get the height of a block in a bar graph?

divide the % in the class by the length of the interval.

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What is the distribution of a variable?

-possible values of the variable

-their relative frequencies

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Two number summary

average

SD

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Z score (Standard units)

z = (Height - Average)/SD

Original Units Height = Average + Z(SD)

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Point of Averages

The average of y only goes up r x SDy when x goes up 1 SD

SD x on x axis

r(SDy) on y axis

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Regression Line

Smoothed version of the graph of averages. If the averages follow a straight line, that line is the regression line.

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Five number summary

Average, SD, quartiles, and R

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Regression Line	Straight line that describes how a response variable y changes an explanitory variable x changes
slope of a regression line	y(hat) = a + b(x) rate at which the predicted response y(hat) changes along the line as the explanitory variable x changes.
Observational Study	observes individuals and measures variables of interest but does not attempt to influence the responses. The purpose of an observational study os to describe some group or situation.
Experiment	deliberately imposes some treatment on individuals in order to observe their respponses. The purpose of an experiment is to study whether the treatment causes a change in the response. When the goal is understanding cause and effect, experiments are the only source of fully convincing data.

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Confounding Variables	Two variables (explanitory or lurking variables) are confounded when their effects on a response variable cannot be distinguished from eachother.
Methods of Comparison	Statisticians use the methos of comparison when they want to know whether... A new vaccine will lower the rate of influenza Psychological environment affeccts brain anatomy educational standards affect test scores Vitamin C prevents or shortens colds
Treatment Vs. Control	Treatment: Group actually being treated Control: Group recieving a placebo Used in experiments
Randomization	1. Minimizes the bias - compare Salk Field Trial with NIFP 2. Calculate chance

Generated by

Koofers.com

Methods of Comparison	Exposed vs. unexposed Experiments: -Key Variables are held constant -Control over group assignment, where... -Impartial chance, called randomization, works best -Treatments are interventions, where... -The goal is a description of the effect.
Observational Studies	-No control over group assignment, often self selection or exposure by association -observations, not interventions -Key variables may vary, so...confounding is always a risk -Matching, strategic, but not always effective.
What is significant about self selection for experiments?	Confounding: not as random
Confounding variables	observational studies associate with smoking but correlates with alcohol - correlates with exposure and outcome an dgets mixed up -Lurking variable

Generated by

Koofers.com

What kind of experiment was the Clofibrate Trial?	some people were adherers, some were non semi-observational study
What does a histogram measure?	-Demographic variables, like age, education, and income; -Psychological variables like height, weight, blood pressure, and serum cholestorol levels; -Dietary habbits; -Prevalence of diseases, like diabetes or obesity.
Bar graphs show what kind of data	-Demographic variables like age, sex, race; -Employment status like employed, unemployed, or outside the labor force; -Incomes like annual wage, salary, wage rates, or other sources.
Qualitative Variables	Variables which classify subjects into two or more categories or nominal groups... -Sex, race, employment, disease type -Bar charts

Generated by

Koofers.com

Quantitative Variables	Variables which measure characters of subjects on numerical scales with a well defined measure. -blood pressure, weight, annual income, age, etc -Histograms
How do you get the height of a block in a bar graph?	divide the % in the class by the length of the interval.
What is the distribution of a variable?	-possible values of the variable -their relative frequencies
Two number summary	average SD

Generated by

Koofers.com

Z score (Standard units)	z = (Height - Average)/SD Original Units Height = Average + Z(SD)
Point of Averages	The average of y only goes up r x SDy when x goes up 1 SD SD x on x axis r(SDy) on y axis
Regression Line	Smoothed version of the graph of averages. If the averages follow a straight line, that line is the regression line.
Five number summary	Average, SD, quartiles, and R

Generated by

Koofers.com

List View: Terms & Definitions

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	Front	Back
	Regression Line	Straight line that describes how a response variable y changes an explanitory variable x changes
	slope of a regression line	y(hat) = a + b(x) rate at which the predicted response y(hat) changes along the line as the explanitory variable x changes.
	Observational Study	observes individuals and measures variables of interest but does not attempt to influence the responses. The purpose of an observational study os to describe some group or situation.
	Experiment	deliberately imposes some treatment on individuals in order to observe their respponses. The purpose of an experiment is to study whether the treatment causes a change in the response. When the goal is understanding cause and effect, experiments are the only source of fully convincing data.
	Confounding Variables	Two variables (explanitory or lurking variables) are confounded when their effects on a response variable cannot be distinguished from eachother.
	Methods of Comparison	Statisticians use the methos of comparison when they want to know whether... A new vaccine will lower the rate of influenza Psychological environment affeccts brain anatomy educational standards affect test scores Vitamin C prevents or shortens colds
	Treatment Vs. Control	Treatment: Group actually being treated Control: Group recieving a placebo Used in experiments
	Randomization	1. Minimizes the bias - compare Salk Field Trial with NIFP 2. Calculate chance
	Methods of Comparison	Exposed vs. unexposed Experiments: -Key Variables are held constant -Control over group assignment, where... -Impartial chance, called randomization, works best -Treatments are interventions, where... -The goal is a description of the effect.
	Observational Studies	-No control over group assignment, often self selection or exposure by association -observations, not interventions -Key variables may vary, so...confounding is always a risk -Matching, strategic, but not always effective.
	What is significant about self selection for experiments?	Confounding: not as random
	Confounding variables	observational studies associate with smoking but correlates with alcohol - correlates with exposure and outcome an dgets mixed up -Lurking variable
	What kind of experiment was the Clofibrate Trial?	some people were adherers, some were non semi-observational study
	What does a histogram measure?	-Demographic variables, like age, education, and income; -Psychological variables like height, weight, blood pressure, and serum cholestorol levels; -Dietary habbits; -Prevalence of diseases, like diabetes or obesity.
	Bar graphs show what kind of data	-Demographic variables like age, sex, race; -Employment status like employed, unemployed, or outside the labor force; -Incomes like annual wage, salary, wage rates, or other sources.
	Qualitative Variables	Variables which classify subjects into two or more categories or nominal groups... -Sex, race, employment, disease type -Bar charts
	Quantitative Variables	Variables which measure characters of subjects on numerical scales with a well defined measure. -blood pressure, weight, annual income, age, etc -Histograms
	How do you get the height of a block in a bar graph?	divide the % in the class by the length of the interval.
	What is the distribution of a variable?	-possible values of the variable -their relative frequencies
	Two number summary	average SD
	Z score (Standard units)	z = (Height - Average)/SD Original Units Height = Average + Z(SD)
	Point of Averages	The average of y only goes up r x SDy when x goes up 1 SD SD x on x axis r(SDy) on y axis
	Regression Line	Smoothed version of the graph of averages. If the averages follow a straight line, that line is the regression line.
	Five number summary	Average, SD, quartiles, and R

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