T-Test: Excel

Summary

T-tests can be extremely helpful in the world of educational research. There are two types of t-tests, independent t-tests and dependent t-tests. The former is used when comparing a difference between two groups given two continuous and categorical variables. The latter is used when comparing the same group on two separate occasions; it is used to determine whether a change has occurred or there is a difference for the group from the one occasion to the next. For example, I took the same data from the National Center for Education Statistics (NCES) that I used previously (2011 reading scores for boys and girls in the fourth grade) and conducted an independent t-test. The categorical independent variable was gender and the continuous dependent variable is the fourth grade. When conducting a t-test, one will either conclude that there is no significant statistical difference (the p value is less than .05), in other words, the null hypothesis is accepted or one will conclude that there is a statistically significant difference (the p value is greater than .05), in other words, the null hypothesis is rejected. By looking through this site I was better able to understand both types of t-tests.

What I Did

            I had previously exported the data I wanted from the NCES into Excel and accessed the Analysis ToolPak add-in. Below are the steps I took to conduct the t-test analysis.

1.      Chose Data from toolbar

2.      Scrolled down to choose T-test: Two Sample Assuming Equal Variances

3.      Filled in Variable 1 Range by clicking and dragging the cursor to select all scores earned by males (same for Variable 2 Range for females)

4.      Titled the new sheet by filling in New Worksheet Ply section

The t-test analysis opened in a new sheet.

If you don’t have Excel, you can still analyze your data in a t-test by using this free online t-test calculator.

What I Learned

Research Question: Does student’s gender impact 4^th grade reading performance?

Hypotheses:

·         Null Hypothesis- There is no statistical difference between the fourth grade readings scores earned by males and females. Gender does not impact fourth grade reading performance.

·         There is a statistical difference between the fourth grade reading scores earned by males and females. Gender does impact fourth grade reading performance.

Critical P-level (alpha): P=0.05

 

Decision rule: Reject null hypothesis since 1-tail p value > 0.05

 

Summary Statement: Reject null hypothesis, 1.611E-07 (tail p value) <= 0.05

 

Statement of Results: There is a statistically significant difference between the 2011 fourth grade reading scores earned by males and females. Gender does impact fourth grade reading performance.

Research Topic for Students Using a T-Test

            Gathering data and analyzing data for a t-test is a fairly straight forward and simple process. However, I do not believe that I would have elementary or middle school students engage in research using a t-test as the concept behind such statistical analysis is complex for children at the elementary and middle school mathematical achievement levels. However, I believe this type of research could be fun and informative for students at the high school level. For a fun, science experiment using a t-test, I might give students the following research topic.

Research Question: Does preservation method (to be determined by students) impact the life span of a carved pumpkin?

Suggested Design: Each student is given a pumpkin (granted that there is an even number of students). Each pumpkin must be similar in weight, shape, and size. Students will carve their pumpkins, creating two eyes, a nose, and a mouth. Half of the students, randomly selected, will use a particular preservation method (ex. acrylic spray) and the other students will use an alternative method (ex. pumpkin fresh spray). Students will observe their own pumpkin every day. Once the pumpkin matches this description the, profuse mold and rot (more than one student will confirm), the pumpkin will be considered deceased and the student will plug into a classroom Excel document, how many days the pumpkin lasted since its carving. The Excel document will have two columns labeled by preservation method. The students will each practice using the t-test function in Excel and the class will discuss the findings. Throughout the process, each student will maintain notes and complete a lab report.

Dependent, Continuous Variable: Life Span of Carved Pumpkins

 

Independent, Categorical Variable: Preservation Method

 

Hypotheses:

·         Null Hypothesis- There is no statistically significant difference between the numbers of days the pumpkins lasted before being confirmed deceased due to profuse mold and rot. Preservation method does not impact the life span of a carved pumpkin.  

·         There is a statistically significant difference between the numbers of days the pumpkins lasted before being confirmed deceased due to profuse mold and rot. Preservation method does impact the life span of a carved pumpkin.

 

Ideas for preservation methods can be found on this site.

Standards Reflection

Conducting educational research using digital age tools towards a goal of evaluating and reflecting upon teaching practices in order to better support student learning meets standard Five "c" of the ISTE-NETS-T’s standards.

Adapting educational experiences by incorporating student use of digital applications such as Excel meets standard two of the ISTE-NETS-T’s standards and its components.

Working With Data (Descriptive Stats): Excel

Summary & What I Learned

     Today I learned about the National Center for Education Statistics (NCES). The NCES website is a government run website through which collected and analyzed data is presented to the public. The NCES collects data on a national scale and therefore, is able to present data comparing state scores across the country.

     To keep the data organized, there is a simple selection process through which the essential data is targeted, minimizing what is presented. Statistics are available for fourth grade, eighth grade, and twelth grade for reading, mathematics, science, and writing. Comparisons can be made by gender, race/ethnicity, lunch eligibility, and percentiles. Data can be displayed from a single year or across years. The data available shows scores every other year from 2000 to 2011. Once the selections are made, a data table will be displayed which can also be exported into Microsoft Excel.

 

 

     In Excel, formulas can be applied to the data for a particular use. In a recent stats class, I learned to compute single columns of data one formula at a time. Today, I learned to gather descriptive statistics with just a few clicks using state comparison data from NCES using an Excel add-in. I chose to analyze grade 4 reading scores from 2011 by gender.

 

What I Did

     After exporting the data I wanted from the NCES website, I had to install an add-in for Excel in order to gather the descriptive statistics. Below, are the steps I took to get the add-in.

1. Went to Office button
2. Clicked on Excel options
3. Clicked on Add-ins
4. Chose the Analysis ToolPax

Below are the steps I took to get the stats.

1. Chose Data from toolbar
2. Clicked on new Data Analysis button
3. Chose Descriptive Statistics
4. Clicked an dragged cursor to select data in one column
5. Checked box for Summary Statistics

The data and analysis opened in a new sheet. I double clicked on the new tab to rename the sheet.

I created yet another sheet where I could place a scatter plot of the data for quick reading. This is what I did.

1. Went back to original sheet
2. Chose Insert from toolbar
3. Clicked on Scatter (chose which look I liked)
4. Clicked on Select Data
5. Clicked and dragged to select data
6. Changed axis titles
7. Copy and pasted into new sheet

View Screencast

 

How I Would Use It

     The NCES website is a reliable source through which to gather data for research and papers. I inted to reference it the next time I am in need of statistics regarding local or national schools and students.

     Excel can be a great resource for collecting, organizing, and analyzing data for qantitative research. I intend to use it for these purposes while gathering data for my Teacher Work Sample and as I conduct action research in the class room.

     For my elementary students, I envision them using what they know about charts from mathematics to create charts of their own using Excel. This way, they will be able to manage their own data in order to create accurate and attractive graphs in a most efficient manner.

 

Standards Reflection

     Conducting  educational research using digital age tools towards a goal of evaluating and reflecting upon teaching practices in order to better support student learning meets standard Five "c" of the ISTE-NETS-T’s standards. 

     Adapting educational experiences by incorporating student use of digital applications such as Excel meets standard two of the ISTE-NETS-T’s standards and it's components.