About the Representative Sample Calculator

The Sampling Calculator allows states to establish representative samples of school districts and students to include in the annual post-school data collection effort. It can assist your state in selecting a representative sample of school leavers for the express purpose of addressing SPP/APR Indicator #14. With the aid of this calculator your state will be able to establish a sample of school leavers that is as similar as possible to the population of school leavers with disabilities that leave schools in your state in a particular year.

Contact NPSO Center staff for your user code and password. To gain access, please contact Melissa Moseley, 541-346-0374, mmoseley@uoregon.edu.

If you want to use the calculator to select a representative sample of, say, schools within your largest districts or for another Indicator allowing sampling, contact NPSO staff for suggestions and an additional user code and password.

Sampling Calculator Step-by-Step Directions

Step 1 - Enter district data

Step 2 - Enter state data

Step 3 - Enter number of years in cycle

Step 4 - Calculate

Step 5 - Review sample

Step 6 - Calculate again

Step 7 - (Optional) Change and recalculate

Step 8 - Print and or copy samples

Data will remain in the database; you can edit or add data at any time.  However, the samples you generate will not be electronically saved, remember to save each sample as it is calculated.

Step 1.    Enter identified data for each district in the state for the most current year.  Click the ”add” button.  Please Note: if you do not have data for one of the columns and you leave that column blank, you will not be able to change that column again later for that district. Instead of leaving blank columns, you should use the number 0 and that will enable you to go back later and edit that column for that district.  If you have missing data (i.e. data is not available and will not be available), you have two options to address this problem.  See the Missing Data document.

Column Header Key for District Level Data Table

District Name


District Name and/or District Number



Total number of students with and without disabilities in the district (ADM)



Must be either 0 or 1, where 0 = rural and 1 = urban (based on your state's definitions of "urban" and "rural")



Number of students with IEPs between ages of 14 and 21



Number of students with IEPs between ages of 14 and 21 identified Specific Learning Disability



Number of students with IEPs between ages of 14 and 21 identified Emotional Disturbance



Number of students with IEPs between ages of 14 and 21 identified Mental Retardation



Number of students with IEPs between ages of 14 and 21 identified as All Other disabilities (hearing impairment, visual impairment, orthopedic impairment, other health impairment, deaf-blindness, multiple disabilities, autism, traumatic brain injury, developmental delay [if applicable in your state], speech and language impairment)



Number of students with IEPs between ages of 14 and 21 who are female



Number of students with IEPs between ages of 14 and 21 whose primary race/ethnicity is not White/non-Hispanic



Number of students with IEPs between ages of 14 and 21 who are English Language Learners



Number of students with IEPs between ages of 14 and 21 who dropped out of school in the previous 12 months based on latest available data (based on your state's definition of "dropout")

After the data are entered for a district, click the "add" button to automatically save the data. After a district is added an "edit" link will be available if changes need to be made. It is not necessary to enter all districts in one session. After you log out your data will remain in the database.

Step 2.    Enter data for the state as a whole for the most recent year. After you have entered all of the District Level Data (i.e. filled in all cells in all columns), complete the State Level Data Table.

Column Header Key for State Level Data Table



is the total number of students – those with disabilities and those without – in the state.

For the remaining columns, a percentage must be calculated (formula is in parentheses.)



is the percentage of urban districts in your state. This is a dichotomous variable and was entered as a 0 or 1, where 0=rural and 1=urban, for each district in the District Level Data Table. Enter the percentage of districts in the state that are urban.  (total number of districts with a value of 1/total number of districts in the state.)



is the percentage of special education students on IEPs ages 14 to 21 years of age. (total SPED 14-21/total students 14-21).

Some states cannot “cut” state-level data at the 4-21 year age range. If your state cannot separate students in this way, it is acceptable to use the 6-21 year age range – it will be critical to use this age range for all columns of data in the calculator (total SPED 6-21/total students 6-21).

IMPORTANT -- It is critical to be consistent with the data you enter. As we mentioned above, if you enter data based on special education students in the 14-21 year old range, it will be necessary for you to use this same age range for each of the following columns. But, if you enter district-level data based on special education students in the 6 to 21-year-old age range, it is necessary to use that age range in each of the these columns. If you switch or mix the “slices” of the population between the district-level and state-level data, the tool will not calculate correct percentages and will not produce a valid comparison between the sample and the state.



% of SPED classified as LD (learning disabled) (total LD / total SPED population 14-21)



% of SPED classified as ED (emotionally disturbed) (total ED / total SPED population 14-21)



% of SPED classified as MR (mentally retarded) (total MR / total SPED population 14-21)



% of SPED classified as AO (all other special education disability groups) (total AO / total SPED population 14-21)



% of SPED that are female (total females 14-21 on IEPS / total SPED population 14-21



% of SPED that are from minority ethnic or racial groups (total minority pop 14-21 on IEPs/ total SPED population 14-21)



% of SPED that are ELL (English language learners) (total ELL 14-21 on IEPs / total SPED population 14-21)



% of SPED that are dropouts (total dropout 14-21 on IEPs/ total SPED population 14-21)

Step 3.  

Enter the number of years in you want in your cycle (between 2-6 years into the  “Calculate Representative Sample” cell.  Remember every district must be included at least once in the 6 year SPP cycle; each district over 50,000 ADM will be included in each year.


Step 4.    Click the “Calculate” button.
Step 5.  

Review the “Sample Matrix” to determine if the sample is acceptable. The most acceptable sample may be the one with the fewest highlighted boxes and therefore is most similar to the entire state (+/-3). Please note: you won’t be able to get back to this particular random sample, therefore, if the sample is acceptable, you should either print this screen and/or copy and paste the table into a Word document.

  • Look at the districts to be sampled every year in the cycle.
  • If a district shows up in more than one year, note whether it is a small or large district. If it is a small district, it may be that the district is unique and should only be included in the cycle once. If the district is large, it is probable that you will want to include it in more than one cycle and that you may choose to sample schools within that district each year. If you have questions or if you’d like to use this calculator to identify a sample of schools within large districts, contact the NPSO Center.

Step 6.    If you want to see another random sample, click “Calculate” again. You can continue to “Calculate” until you identify the most acceptable sample. Remember to print this screen and/or copy and paste the samples you think you may want to review.

Step 7.
  Optional – You can also change the number of years in the cycle and recalculate.
Step 8.    Print screen and/or copy and paste the samples you like.
Data will remain in the database; you can edit or add data at any time.  Remember the samples you calculate will not be electronically saved but the original data will be retained.

Save this page as a MS Word document

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