Stats Lab Exam 1 Review
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Questions and Answers

What kind of variable is a student's GPA?

  • Categorical
  • Dependent
  • Quantitative (correct)
  • Independent

    • What is the standard deviation of a dataset with a variance of 16?

  • 4 (correct)
  • 8
  • 256
  • None of the above

    • What type of graph would be most appropriate to display the frequency of different hair colors in a sample of 100 people?

  • Line graph
  • Scatterplot
  • Histogram
  • Bar chart (correct)

    • What is the skewness of a distribution with a skewness statistic of -1.5 and a skewness standard error of 0.3?

    <p>Negatively skewed (D)</p> Signup and view all the answers

    If the p-value of a one-sample t-test is 0.01, what conclusion can we draw?

    <p>The null hypothesis is rejected (C)</p> Signup and view all the answers

    A researcher wants to test if the average height of women is different from 5'4". What are the null and alternative hypotheses?

    <p>H0: µ = 5'4&quot;; H1: µ ≠ 5'4&quot; (C)</p> Signup and view all the answers

    What is the purpose of a one-sample t-test?

    <p>To compare a sample mean to a known population mean (D)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of a normal distribution?

    <p>Tails extend indefinitely in both directions (C)</p> Signup and view all the answers

    What is the appropriate statistical test to use when comparing a sample mean to a known population mean?

    <p>One-sample t-test (A)</p> Signup and view all the answers

    Which of the following is NOT a step involved in performing a one-sample t-test in SPSS?

    <p>Calculate the mean and standard deviation of the sample (B)</p> Signup and view all the answers

    When presenting the results of a one-sample t-test in APA style, what three values are required?

    <p>t-statistic, degrees of freedom, p-value (B)</p> Signup and view all the answers

    What does a p-value less than .05 indicate in a one-sample t-test?

    <p>The sample mean is significantly different from the population mean. (D)</p> Signup and view all the answers

    What is the null hypothesis for a one-sample t-test?

    <p>The sample mean is equal to the population mean. (C)</p> Signup and view all the answers

    Flashcards

    Rejecting the null hypothesis

    Deciding to reject the null hypothesis when p < .05 in SPSS output.

    Recode age groups

    Transform continuous age data into categorical values (e.g., 18-25 = 1).

    One sample t-test reporting

    Report t value, degrees of freedom (df), and p value in APA style.

    Nominal variables

    Categorical variables without a numeric value (e.g., gender).

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    Skewness

    A measure of the asymmetry of a probability distribution (e.g., positive skew).

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    Interval Variable

    Numerical variables with meaningful quantitative differences.

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    Dependent Variable

    A variable thought to be a result of another variable.

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    Mean

    The sum of values divided by the number of values in a group.

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    Standard Deviation

    A statistic that measures the average variability of a dataset.

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    Null Hypothesis

    The hypothesis stating there is no effect or difference; used in hypothesis testing.

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    Outlier

    A data point that significantly differs from other observations.

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    Study Notes

    Variables

    • Nominal variables have categories without quantitative differences.
    • Scale variables describe numerical variables with meaningful differences.
    • A dependent variable is a result of another variable.
    • An independent variable causes an effect.
    • Examples of categorical variables include religious affiliation and letter grades.

    Descriptive Statistics

    • The mean is the sum of all numbers divided by the count.
    • Variability, or spread, of the data can be estimated via standard deviation.
    • In SPSS, use the AVERAGE function to calculate the average of multiple variables.
    • In SPSS, use the Analyze > Descriptive Statistics > Frequencies menu to get descriptive statistics.
    • Standard deviation squared is variance.

    Graphing

    • The image is a bar graph.
    • A bar graph visually displays categories and their respective values.
    • The dependent variable on a bar graph goes on the y-axis or vertical axis.

    Old Faithful Eruptions

    • The graph shows the relationship between eruption duration and waiting time.
    • The graph is a scatter plot, displaying data points as (x, y) coordinates.
    • The line on the scatter plot is the linear regression line.

    Skew and Kurtosis

    • Skewness describes the asymmetry of a distribution.
    • Kurtosis measures the "tailedness" or peak of a distribution.
    • A normal distribution is symmetrical with a kurtosis of 3.

    One Sample t-tests

    • In a one-sample t-test, the sample mean is compared to a population mean.
    • Statistical significance is typically defined as a p-value less than 0.05.
    • If p is equal to or less than 0.05, the null hypothesis is rejected.
    • The null hypothesis is rejected when the p value is less than 0.05.
    • A one sample t-test in SPSS utilizes 'Analyze' > 'Compare Means' > 'One-Sample T Test'. The input value is the population mean value.

    Miscellaneous

    • Box plots, often called box-and-whisker plots, display data distribution.
    • The p-value is the criterion for rejecting the null hypothesis.
    • To recode a variable in SPSS, use the Transform > Recode into Different Variables menu.
    • For APA style, the output values for a one-sample t-test include the t statistic, degrees of freedom, and p-value.

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    Description

    This quiz covers key concepts in statistics, including variables, descriptive statistics, and graphing techniques. Learn about nominal and scale variables, dependent and independent variables, as well as how to analyze data in SPSS. Test your understanding of mean, variability, and graphing data effectively.

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