Assessment 1 Instructions: Descriptive Statistics

Use statistical software to create, interpret, and analyze two histograms in a Word document.

Introduction

Descriptive statistics are just what they sound like, statistics that allow you to describe or summarize the data with regard to such things as their distribution and their spread. Descriptive statistics provide you with a picture of your data while inferential statistics (which we will discuss in subsequent assessments) allow you to draw conclusions about relationships between variables or differences between groups.

A solid understanding of descriptive statistics is foundational to grasping the concepts presented in inferential statistics. This assessment measures your understanding of key elements of descriptive statistics.

Your first statistical software assessment includes two sections in which you will do the following:

1. Create two histograms.

2. Calculate measures of central tendency and dispersion.

This will give you some experience with the data set.

Key Details and Instructions

• Submit your assessment as a Word document.

• Refer to the JASP Step-by-Step: Histograms and Descriptive Statistics [PDF] document for additional help in completing this assessment.

• View JASP Speedrun: Descriptive Statistics [Video] for a brief tutorial on this assessment.

• As you work on this assessment, refer to the 7864 Data Set Instructions [PDF] file for information on variables used in this course.

• Provide a title for your document and your name.

Download the 7864 data set, grades.jasp, which is a sample data set, and save it to your computer. The data represent a teacher’s recording of student demographics and performance on quizzes and a final exam. For this assessment, you will create and describe two histograms and a descriptives table using these data.

Section 1: Histograms for Visual Interpretation

Using the final and lowup variables in your grades.jasp data set, create two histograms and paste them into your Word document:

Variable Definition

Lowup lower division =1; Upper division =2

Final Final exam: number of correct answers

Variables and Definitions

Create:

• A histogram for lower division.

• A histogram for upper division.

Briefly describe what a visual inspection of this output tells you about the shape of the distributions.

Section 2: Calculate Measures of Central Tendency and Dispersion

Using the grades.jasp file, compute descriptive statistics, including mean, standard deviation, skewness, and kurtosis for gpa and quiz3.

Variable Definition

GPA Previous grade point average

Quiz3 Quiz 3: number of correct answers

Variables and Definitions

Create a descriptives table and paste it into your Word document.

Under the table:

• Report the mean, standard deviation, skewness, and kurtosis for GPA and quiz3.

• Briefly describe what skewness and kurtosis tell you about these data with regard to normality.

Submit both sections of your assessment as an attached Word document.

Software

The following statistical analysis software is required to complete your assessments in this course:

• Jeffreys’s Amazing Statistics Program (JASP).

Refer to the Tools and Software: JASP page on Campus for general information. Make sure that your statistical software is downloaded, installed, and running properly on your computer.

Competencies Measured

By successfully completing this assessment, you will demonstrate your proficiency in the course competencies through the following assessment scoring guide criteria:

• Competency 4: Interpret the results of statistical analyses.

o Below the output, provide an accurate interpretation of histograms for lower division students and upper division students.

o Below the output, report descriptive statistics and interpret skew and kurtosis values.

• Competency 5: Apply a statistical programs procedure to data.

o Provide histograms for lower division students and upper division students.

o Provide a descriptive statistics table.

7864 Data Set Instructions

The 7864 data set is fictional data. The data represents a teacher’s recording of student

demographics and academic performance across three sections of their course. Each course

section consists of about 35 students (N = 105).

The data set is located on grades.jasp. You can download grades.jasp from the 7864

assignments instructions area. It will then open in JASP.

There are 21 variables in the course data set. Refer to the table below.

Scale of

JASP variable Definition Values measurement

id Student identification number Nominal

lastname Student last name Nominal

firstname Student first name Nominal

1 = woman; 2 = man; 3 =

transgender; 4 = non- genderidentity Student gender identity Nominal binary/non-conforming; 5 =

prefer not to disclose

1 = Native American; 2 = Asian;

ethnicity Student ethnicity 3 = Black; 4 = White; 5 = Nominal

Hispanic

1 = freshman; 2 = sophomore;

year Class rank Ordinal 3 = junior; 4 = senior

lowup Lower or upper division 1 = lower; 2 = upper Nominal

section Class section

gpa Previous grade point average Scale

extcr Did extra credit project? 1 = no; 2 = yes Nominal

review Attended review sessions?

quiz1 Quiz 1: number of correct answers

quiz2 Quiz 2: number of correct answers Scale

Nominal

1 = no; 2 = yes Nominal

Scale

quiz3 Quiz 3: number of correct answers Scale

quiz4 Quiz 4: number of correct answers Scale

1

Scale of

JASP variable Definition Values measurement

quiz5 Quiz 5: number of correct answers Scale

Final exam: number of correct final Scale

answers

total Total number of points earned Scale

percent Final percent Scale

grade Final letter grade (A, B, C, D, F) Nominal

Passed or failed the course? 1 = passfail Nominal pass; 0 = fail

2

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Section 1: Histograms for Visual Interpretation

Open the JASP software and load the “grades.jasp” data set.

Identify the variables “Lowup” and “Final” in the data set. “Lowup” represents the division (lower or upper), and “Final” represents the final exam scores.

Create a histogram for the “Lowup” variable to visualize the distribution of lower division and upper division students. The histogram will display the frequency of each division.

Create a separate histogram for the “Final” variable to visualize the distribution of the final exam scores.

Take screenshots or export the histograms and paste them into your Word document.

Describe what the shape of the distributions tells you based on your visual inspection of the histograms. Look for information such as whether the distributions are symmetrical, skewed to the left or right, or bimodal.

Section 2: Calculate Measures of Central Tendency and Dispersion

Use the “grades.jasp” data set in JASP.

Identify the variables “GPA” and “Quiz3” in the data set. “GPA” represents the previous grade point average, and “Quiz3” represents the number of correct answers on Quiz 3.

Calculate the mean, standard deviation, skewness, and kurtosis for both the “GPA” and “Quiz3” variables.

Create a descriptives table that includes the calculated statistics for “GPA” and “Quiz3”.

Take a screenshot or export the descriptives table and paste it into your Word document.

Report the mean, standard deviation, skewness, and kurtosis for both “GPA” and “Quiz3” in your Word document.

Briefly describe what skewness and kurtosis tell you about the data with regard to normality. Skewness measures the asymmetry of the distribution, and kurtosis measures the peakedness of the distribution. Interpret these values in terms of whether the distributions are approximately normal or exhibit deviations from normality.