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PSYC 258: Chapter 1 Terminology & Scales of Measurement

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Page 1: class notes

PSYC 258: Chapter 1

Terminology & Scales of Measurement

Page 2: class notes

Preview

Terminology

Scales of Measurement

Notation & Math Basics

Page 3: class notes

Learning Objectives

By the end of this class you should be able to…

1. Apply terminology relevant to the field of Statistics

2. Compare the different scales of measurement and give examples of each

3. Explain why scales of measurement matter

4. Properly use symbols and basic math rules

Page 4: class notes

Terminology

What is Statistics?

What are the two branches?

What types of questions can Statistics answer?

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Terminology

What is a Hypothesis?

Hypothesis “an educated guess”

Hypothesis a testable prediction (based on prior evidence)

Page 6: class notes

Terminology

Null Hypothesis everything that does not support what the researcher wants to find; what is already assumed

Research Hypothesis what the researcher wants to find evidence to support

Page 7: class notes

Terminology

We are interested in creativity. We believe people that are awake at night (and sleep during the day) are more creative than those that are awake during the day (and sleep at night). We collect a sample of 30 people from across the country, 15 of those people are awake at night, and 15 of those people are awake during the day.

What is the research hypothesis?

What is the null hypothesis?

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Terminology

Something that is the same for everyone is C_______

Something that can take-on one or more values is a V_______

2X + 8, X is a _______

Person A’s height is a _______

Person A’s gender is a _______

Person A’s name is a _______

Is “4” a variable?

Is “male” a variable?

Page 9: class notes

Terminology

What is the difference between an Independent Variable and a Dependent Variable?

Independent Variable (IV) a variable that can be manipulated

Dependent Variable (DV) a variable that is expected to be influenced by the manipulated variable, measured but not manipulated

Page 10: class notes

Terminology

We are interested in creativity. We believe people that are awake at night (and sleep during the day) are more creative than those that are awake during the day (and sleep at night). We collect a sample of 30 people from across the country, 15 of those people are awake at night, and 15 of those people are awake during the day.

What is the IV?

What is the DV?

Page 11: class notes

Terminology

Extraneous Variables other variables that may influence the dependent variable but are not manipulated, stuff we are not interested in (nuisance variables)

Want to “control” extraneous variables

(Related to chance)

Page 12: class notes

Terminology

We are interested in creativity. We believe people that are awake at night (and sleep during the day) are more creative than those that are awake during the day (and sleep at night). We collect a sample of 30 people from across the country, 15 of those people are awake at night, and 15 of those people are awake during the day.

What could be an extraneous variable?

Page 13: class notes

Terminology

What is the difference between a Population and a Sample?

Population everyone (or thing) of interest

Sample part of the population

Page 14: class notes

Terminology

We are interested in creativity. We believe people that are awake at night (and sleep during the day) are more creative than those that are awake during the day (and sleep at night). We collect a sample of 30 people from across the country, 15 of those people are awake at night, and 15 of those people are awake during the day.

What is the population?

What is the sample?

Page 15: class notes

Terminology

What is the difference between a Statistic and a Parameter?

Statistic a value describing a sample

Parameter a value describing the population

Page 16: class notes

Terminology

Sample - Statistic Population - Parameter

Estimate statistics used to approximate parameters

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Scales of Measurement

Scales of measurement different classes of variables

Nominal groups (gender, ethnicity, etc.)

Page 18: class notes

Scales of Measurement

Ordinal groups, but there is an order (class level)

Interval numbers with an equal distance between each value (Likert scale)

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Scales of Measurement

Ratio numbers with an equal distance between each value AND zero means absence (height, salary, age, etc.)

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Scales of Measurement

Which are rankings (1st 2nd 3rd …)? Why?

Which is temperature Fahrenheit?

Which is temperature Celsius?

Which is temperature Kelvin?

Are negative numbers allowed for ratio variables?

Which is your net worth?

What is required to be ratio?

Page 21: class notes

Scales of Measurement

Why do these scales matter?

To say “twice as much” Ratio To say “5 points more” Interval (or

Ratio) To say “more” Ordinal (or Interval or

Ratio) Can only say “different” with Nominal

Page 22: class notes

Scales of Measurement

Ratio holds the most info… and we can always “downgrade” ratio into any of the other types

Also influences the statistics we can calculate (mean, standard deviation) and tests we can perform (t, regression, ANOVA, Chi-Square…)

Page 23: class notes

Scales of Measurement

Nominal and ordinal are collectively called categorical or qualitative

Interval and ratio are collectively called continuous or quantitative

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Symbols & Math

Symbols

What is PEMDAS?

How should we round 2.48276?

257.469?

13.795218?

4?

*Critical values and probabilities*

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Review

What is a hypothesis?

Give an example of a null and research hypothesis

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Review

What is an independent variable?

What is a dependent variable?

What is an extraneous variable?

Page 27: class notes

Review

What is the relationship between populations, samples, statistics and parameters?

What is an estimate?

Page 28: class notes

Review

Give an example of a variable measured on a nominal scale

An ordinal scale

An interval scale

A ratio scale

Page 29: class notes

Preview

Today we talked about Statistics in general and defined some key terms

Next time we will talk about graphing and organizing data