Study Creation and Configuration

Overview

The Study Creation module lets you configure all parameters needed to run a statistically valid work sampling study. The guided form ensures you don't forget any important data.

Form Fields

Basic Information

Field	Description	Required
Study name	Unique identifier for the study (e.g., "Production Line A - Q1 2025")	✅ Yes
Company	Client company or department name	❌ No
Technician/Analyst	Name of the person responsible for the study	❌ No
Department	Area or section where the study is performed	❌ No
Objectives	Description of what is intended to be analyzed	❌ No
Notes	Additional observations about the study	❌ No

Study Dates

Start date: First day of observations
End date: Last day of observations

The study duration directly affects the number of days available to distribute the required observations.

Statistical Parameters

📐 Key statistical concepts

Confidence Level: Probability that the results fall within the error margin. Options: 90%, 95% (recommended), 99%
Error Margin (Precision): Maximum acceptable error in the results. Typically ±5% for standard studies, ±3% for high precision.
Estimated Proportion (p): Initial estimate of the % of time spent on the main activity. Use 50% if you don't have prior data (maximizes the required sample size).

Automatic Sample Size Calculation

The application automatically calculates the number of required observations using the statistical formula:

n = (Z² × p × (1-p)) / E²

Where: Z = Z-value for confidence level, p = estimated proportion, E = error margin

Confidence Level	Error Margin	p = 50%	p = 30%
90%	±5%	271 obs.	228 obs.
95%	±5%	385 obs.	323 obs.
95%	±3%	1,068 obs.	897 obs.
99%	±5%	666 obs.	559 obs.

Allowances Configuration

Allowances are additional percentages added to normal time to obtain standard time. They include:

Personal needs (5%)
Basic fatigue (4%)
Variable fatigue (depending on conditions)
Inevitable delays

Typical value: 15% for standard industrial work.

Pace Rating Scale

The application supports two performance rating scales:

100-133 Scale

ILO / Centesimal

100 = Normal pace
133 = Maximum incentive pace

60-80 Scale

Bedaux / BSI

60 = Normal pace
80 = Maximum incentive pace

Preliminary Observations

Optionally you can enter data from a previous pilot study:

Number of preliminary observations: How many observations were made
Observed % productive: Percentage of productive time found

This data helps refine the estimated proportion (p) and obtain a more precise final sample size calculation.

Editing Studies

Existing studies can be edited at any time. However, keep in mind:

Changing dates may require regenerating the observation plan
Modifying statistical parameters will affect the required number of observations
Already collected data is not lost when editing

⚠️ Important

Carefully review all parameters before starting to record observations. Although you can edit later, it's better to have the correct configuration from the start.