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Introduction to Policy Introduction to Policy ProcessesProcesses

Dan Laitsch

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OverviewOverview

Sign inBusiness

– Crashed blog– Grades and extensions

Review last class– Stats– Research– Policy

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Class 2: Review Class 2: Review

Stats– Mean, median, mode– Variability– Correlations– Reliability and Validity

Research– Thanks tanks, advocacy, scholarship

Policy– Institutional rational choice– Multiple streams– Social construction

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Class 3 AgendaClass 3 Agenda

Review Stats

– Hypotheses– Probability

PBL groups Small groups: Role play prep -Lunch- Role plays Policy readings PBL Groups

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Part III: Part III: Taking Chances for Fun Taking Chances for Fun and Profitand Profit

Chapter 7 Hypotheticals and You: Testing Your Questions

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What you learned in Chapter 7What you learned in Chapter 7

– The difference between samples and populations

– The importance of…The null hypothesisThe research hypotheses

– How to judge a good hypothesis

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What is a hypothesis?What is a hypothesis?

An “educated guess”

Role is to reflect the general problem statement or question that is driving the research

Translates the problem or research question into a form that can be tested.

Not all good research requires a hypothesis

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Samples and PopulationsSamples and Populations

Population– The large group to which you would like to

generalize your findings Sample

– The smaller, representative group of the population that is used to do the research

Sampling error – a measure of how well a sample represents the population

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The Null HypothesisThe Null Hypothesis

Statements that contain two or more things that are equal (or unrelated) to one another

H0 : 1 = 2

– E.g. there is no difference between the two groups– Starting point and is accepted as true without knowing

more information– Benchmark to compare actual outcomes

0912:,H=0912:,H=

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The Research HypothesisThe Research Hypothesis

Statement that there is a relationship between two variables

Two Types…– Nondirectional -- H1 : X1

≠ X2Reflects a difference; direction is not specifiedTwo-tailed test

– Directional -- H1 : X1 > X2Reflects a difference; direction is specifiedOne-Tailed test

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Null & Research HypothesesNull & Research Hypotheses

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Differences Between Null and Differences Between Null and Research HypothesesResearch Hypotheses

Null Research

No relationship between variables

Relationship between variables

Refers to the population Refers to the sample

Indirectly tested Directly tested

Written using Greek symbols Written using Roman symbols

Implied hypothesis Explicit hypothesis

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What Makes a Good Hypothesis?What Makes a Good Hypothesis?

Stated in a declarative form rather than a question

Defines an expected relationship between variables

Reflects theory or literature on which they are based

Brief and to the point Testable – include variables that can be measured

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Glossary Terms to KnowGlossary Terms to Know

Hypothesis– Null Hypothesis

– Research Hypothesis Direction & Non-directional hypotheses One-tailed & Two-tailed test Population Sample

– Sampling error

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Part III: Taking Chances for Fun and Part III: Taking Chances for Fun and ProfitProfit

Chapter 8 Are Your Curves Normal? Probability and Why it Counts

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What you learned in Chapter 7What you learned in Chapter 7

Understanding probability is basic to understanding statistics

Characteristics of the “normal” curve– i.e. the bell-shaped curve

All about z scores– Computing them– Interpreting them

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Why Probability?Why Probability?

Basis for the normal curve– Provides basis for understanding probability of

a possible outcomeBasis for determining the degree of

confidence that an outcome is “true”– Example:

Are changes in student scores due to a particular intervention that took place or by chance alone?

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The Normal Curve The Normal Curve (a.k.a. the Bell-Shaped Curve)(a.k.a. the Bell-Shaped Curve)

Visual representation of a distribution of scores

Three characteristics…– Mean, median, and mode are equal to one

another– Perfectly symmetrical about the mean– Tails are asymptotic (get closer to horizontal

axis but never touch)

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The Normal CurveThe Normal Curve

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Hey, That’s Not Normal!Hey, That’s Not Normal!

In general, many events occur right in the middle of a distribution with few on each end.

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More Normal Curve 101More Normal Curve 101

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More Normal Curve 101More Normal Curve 101

For all normal distributions…

– almost 100% of scores will fit between -3 and +3 standard deviations from the mean.

– So…distributions can be compared

– Between different points on the X-axis, a certain percentage of cases will occur.

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What’s Under the Curve?What’s Under the Curve?

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The The zz Score Score

A standard score that is the result of dividing the amount that a raw score differs from the mean of the distribution by the standard deviation.

What about those symbols?

( ),

X Xz

s

−=

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TheThe zz ScoreScore

Scores below the mean are negative (left of the mean) and those above are positive (right of the mean)

A z score is the number of standard deviations from the mean

z scores across different distributions are comparable

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What What zz Scores Represent Scores Represent

The areas of the curve that are covered by different z scores also represent the probability of a certain score occurring.

So try this one…– In a distribution with a mean of 50 and a

standard deviation of 10, what is the probability that one score will be 75 or above?

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The Difference between The Difference between zz scores scores

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What What zz Scores Really Scores Really RepresentRepresentKnowing the probability that a z score

will occur can help you determine how extreme a z score you can expect before determining that a factor other than chance produced the outcome

Keep in mind… z scores are typically reserved for populations.

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Hypothesis Testing & Hypothesis Testing & zz ScoresScoresAny event can have a probability

associated with it.– Probability values help determine how

“unlikely” the even might be– The key --- less than 5% chance of occurring

and you have a significant result

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Glossary Terms to KnowGlossary Terms to Know

ProbabilityNormal curve

– AsymptoticStandard Scores

– z scores

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Small Group Roll PlaySmall Group Roll Play

Break into groups and plan role play

Lunch

Commence role play

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Policy ReadingsPolicy Readings

Chapters 17-20– Political Parties– Business Associations– Labour Movement– Voluntary Sector

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For Next ClassFor Next Class

Assignments for next class– Research Review. Small group work (as assigned by

the group). Readings:

– Studying Your Own School, Chapter 5– Statistics for People Who (think they) Hate Statistics,

Part 4 (Chapters 9-11)– Theories of the Policy Process: Part 3 & 4 (Chapters 5,

7, 8, 9)– Policy Analysis in Canada: Part 6 (Chapters 21-23)

End of day 2