Psychology Week 3 Summary Quiz
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Questions and Answers

What type of distribution is this?

A normal distribution

Determining a person's reaction time (in milliseconds would involve measurement of a(n) ____ scale of measurement?

ratio

The participants in a research study are classified as high, medium, or low in self-esteem. This classification involves measurement on a nominal scale.

False (B)

In a correlational study, _____.

<p>Two variables are measured and there is only one group of participants</p> Signup and view all the answers

In the simplest experimental study, _____.

<p>One variable is measured and two groups are compared</p> Signup and view all the answers

In a research study comparing attitude scores for males and females, participant gender is an example of what kind of variable?

<p>A quasi-independent variable</p> Signup and view all the answers

What is the goal of central tendency?

<p>To find the single score that is most typical or most representative of the entire group</p> Signup and view all the answers

What is the mean?

<p>A &quot;balance point&quot; – the distances above the mean have the same total as the distances below the mean</p> Signup and view all the answers

What is mode?

<p>The score/value that occurs most often</p> Signup and view all the answers

When is the median preferred?

<p>When the data contains extreme scores (A), When the distribution is skewed (C), When there are undetermined or unknown values within the data set (D), When you have an open-ended distribution (E), When you are using an ordinal scale (F)</p> Signup and view all the answers

When is mode preferred?

<p>When you are using a nominal scale (E)</p> Signup and view all the answers

What does variability refer to?

<p>provides a quantitative measure of the differences between scores in a distribution and describes the degree to which the scores are spread out or clustered together</p> Signup and view all the answers

What is the formula for range?

<p>range = Xmax - Xmin</p> Signup and view all the answers

What is the equation for deviation score?

<p>deviation score = X - μ</p> Signup and view all the answers

What is variance?

<p>equals the mean of the squared deviations</p> Signup and view all the answers

What is standard deviation?

<p>the square root of the variance</p> Signup and view all the answers

What is the sum of squares?

<p>sum of the squared deviations</p> Signup and view all the answers

What is the formula for population variance?

<p>σ² = SS / N</p> Signup and view all the answers

What is the formula for population standard deviation?

<p>σ = √σ²</p> Signup and view all the answers

The basic assumption of inferential statistics is that samples should be representative of the populations from which they are drawn.

<p>True (A)</p> Signup and view all the answers

Samples consistently tend to be more variable than their populations.

<p>False (B)</p> Signup and view all the answers

What is the formula for sample variance?

<p>s² = SS / (n - 1)</p> Signup and view all the answers

What is the formula for sample standard deviation?

<p>s = √s²</p> Signup and view all the answers

What are degrees of freedom?

<p>The number of scores in the sample that are independent and free to vary.</p> Signup and view all the answers

How is the concept of degrees of freedom used in this context?

<p>It allows us to determine what the missing datum is, regardless of which data set we use</p> Signup and view all the answers

What does it mean for a sample statistic to be unbiased?

<p>If the average value of the statistic is equal to the population parameter</p> Signup and view all the answers

Sample variance is an unbiased statistic.

<p>True (A)</p> Signup and view all the answers

How is the mean represented in a frequency distribution graph?

<p>by drawing a vertical line and labeling it with μ or M</p> Signup and view all the answers

How is the standard deviation represented in a frequency distribution graph?

<p>by a line or an arrow drawn from the mean outward for a distance equal to the standard deviation and labeled with a σ or an s</p> Signup and view all the answers

Study Notes

Week 3 Summary

  • Course: PSYC*1010(02)
  • Instructor: Skylar J. Laursen, MSc
  • Week: W25

Online Quiz 1

  • Online Quiz 1 Statistics:

    • Average: 84.21
    • Mean: 84.21
    • Median: 84.38
    • Mode: 90.63
    • Standard Deviation: 7.92
    • Range: 40.62
    • Type of Distribution: Unknown, needs further information.

  • Online Quiz 1 – Types of Scales:

    • Reaction time measurement involves a ratio scale.
    • Classifying participants as high, medium, or low in self-esteem involves a nominal scale.

  • Online Quiz 1 – Types of Studies:

    • In a correlational study, two variables are measured, and there is only one group of participants.
    • In a simple experimental study, one variable is measured, and two groups are compared.

Correlational Study

  • Examines relationships between two variables.
  • Example: Number of classes attended and final grade (illustrated by a scatter plot).

Experimental Study

  • Aims to determine cause-and-effect relationships between two variables.
  • Example: Note-taking and quiz performance (illustrated by a bar graph).

Online Quiz 1

  • Participant gender in a study comparing attitude scores for males and females is a quasi-independent variable.

Central Tendency - Recap

  • A statistical measure to determine a single score that represents the center of a distribution.
  • Goal: Identify a typical score.
  • Mean: "balance point" – distances above the mean equal the distances below.
  • Median: Middle of the distribution.
  • Mode: The most frequent score.

Central Tendency Example

  • Example involving final grades for a fourth-year psychology course at a university.
  • Example of calculating the mean of final grades, and obtaining the individual scores.

When to Use Central Tendencies

  • Median: Use when extreme scores exist in the data set, distribution is skewed, or there are undetermined/unknown values.
  • Mode: Use for nominal scales.
  • Mean: Most common; use for all other situations.

Variability

  • A quantitative measure of the differences between scores within a distribution.
  • Describes the distribution (spread of data points).
  • Measures how well an individual score represents the entire distribution.

Variability: The Range

  • The distance between the largest score and the smallest score.
  • Range = Xmax - Xmin
  • Example calculations with IQ scores and change scores from midterm exams.

Standard Deviation and Variance

  • Deviation: Distance from the mean. ((X - μ))
  • Variance: Average squared deviation. (Σ(X - μ)²)/N (or n-1)
  • Standard Deviation: Square root of Variance.
  • Example Calculation based on the number of drinks consumed weekly.

Measuring Variance for a Population

  • Variance = mean squared deviation / number of scores
  • Sum of Squares (SS) = Sum of squared deviations

Measuring Variance for a Population (Definitional Formula)

  • SS = Σ(X - μ)²
    • Step 1: Calculate deviation score
    • Step 2: Square each deviation score
    • Step 3: Add all the squared deviations to find the sum of squares (SS).

Population Variance and Standard Deviation

  • Population Variance = SS / N *(σ²)
  • Population Standard Deviation = √Population Variance *(σ)

Population Variance and Standard Deviation: Example Calculation

  • Example of calculating population variance and standard deviation based on ice cream consumption.

Measuring Variance and Standard Deviation (for a Sample):

  • Sample Variance = Σ(X - M)²/(n-1) , s²
  • Sample Standard Deviation = √sample variance,. s

Sample Variance and Standard Deviation: Example Calculation

  • Example of a sample calculation based on ice cream consumption

Frequency Distribution Histogram and Standard Deviation

  • Visual representation of data using bars to show the frequency of data points in intervals.

Sample Variability and Degrees of Freedom

  • The goal of inferential statistics is to use samples of data, to draw conclusions about populations.
  • Samples tend to be less variable than populations.
  • When looking at a sample, you have to look at the degrees of freedom which is (n -1). (n = sample size).
  • This allows a calculation of variance from the sample size, to allow for appropriate inference about the population.

Hypothetical Examples and Sample calculations

  • Illustrative examples involving hypothetical data sets with missing values to highlight the use of degrees of freedom to identify and calculate missing values.

Sample Variance as an Unbiased Statistic

  • A sample statistic is unbiased if the average value of that statistic equals the corresponding population parameter.

Presenting the Mean and Standard Deviation in a Graph

  • Display frequency distribution graphs where a vertical line is used to identify the mean of the distribution.
  • Standard deviations from the mean, are used to identify ranges on the data distribution.

Means and Standard Deviations - Graph

  • Graphically illustrates the mean and standard deviation of a data set.

Transformations of Scale

  • Adding or subtracting a constant to each value in a distribution does not change the standard deviation.
  • Multiplying each value by a constant does multiply the standard deviation by that constant. Illustration with both theoretical examples, and graphs.

Standard Deviation and Descriptive Statistics

  • Uses both the mean and the standard deviation to provide an overall understanding of the data distribution.
  • The mean and standard deviation allows the reconstruction of the raw data, for further investigation of the particular data set, or to compare with other sets.

Underlying Scale of Measurement

  • Graphically and visually, illustrating how mean and standard deviation are used to present information on x-axis data values.

Variance and Inferential Statistics

  • Variance is important in inferential statistics.
  • Low variance makes easier to identify patterns in a data set.
  • High variance obscures patterns within a data set.

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Related Documents

Week 3 PSYC*1010(02) Online Quiz PDF

Description

Test your knowledge on the concepts of scales, types of studies, and statistics covered in week 3 of PSYC*1010(02). This quiz will help reinforce your understanding of correlational and experimental studies and their implications. Dive into the statistical analysis and measurement types to evaluate your grasp of the material.

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