Free Six Sigma Sample Calculator: Easy Tool


Free Six Sigma Sample Calculator: Easy Tool

Figuring out the suitable variety of knowledge factors is essential for statistical evaluation inside course of enchancment methodologies. A instrument assists in defining this amount to make sure dependable conclusions about course of functionality and efficiency. For example, when assessing the effectiveness of a course of modification, this instrument helps decide what number of measurements are wanted to confidently detect a significant distinction in output, resembling a lower in defect charge.

The usage of such a instrument affords a number of benefits, together with optimizing useful resource allocation by avoiding extreme knowledge assortment, and offering a statistically sound foundation for decision-making. Traditionally, reliance on instinct or arbitrary pattern sizes usually led to inaccurate assessments and ineffective enhancements. Correct pattern measurement willpower enhances the chance of figuring out real course of modifications and avoids the pitfalls of drawing false conclusions based mostly on inadequate or extreme knowledge.

The following dialogue will delve into the statistical underpinnings and sensible software of this important useful resource, outlining the components influencing pattern measurement necessities and offering steering on its efficient implementation in course of enchancment initiatives. Key concerns embrace desired confidence ranges, acceptable margins of error, and estimates of course of variability.

1. Statistical Energy

Statistical energy represents the chance {that a} speculation take a look at will accurately determine a real impact. Within the context of course of enchancment initiatives, attaining enough energy is essential to make sure that carried out modifications genuinely enhance the method reasonably than showing to take action attributable to random variation. Underpowered research danger failing to detect vital enhancements, resulting in wasted assets and missed alternatives for course of optimization.

  • Definition and Significance

    Statistical energy is formally outlined as 1 – , the place is the chance of a Sort II error (failing to reject a false null speculation). In Six Sigma initiatives, the null speculation usually assumes no distinction between the present course of and the improved course of. Low statistical energy will increase the danger of accepting this null speculation when a real enchancment exists, thus hindering progress. The flexibility to detect even small however significant course of modifications requires enough energy.

  • Relationship to Pattern Dimension

    Statistical energy is instantly associated to pattern measurement. Bigger pattern sizes usually result in increased statistical energy, as they supply extra details about the inhabitants below examine and cut back the affect of random noise. The instrument assists in figuring out the minimal pattern measurement required to attain a desired stage of statistical energy for a given course of enchancment undertaking. With out this calculation, initiatives danger being underpowered, whatever the precise affect of the carried out modifications.

  • Influence of Impact Dimension

    The magnitude of the impact that the method enchancment is anticipated to supply, often known as the impact measurement, additionally influences statistical energy. Bigger impact sizes are simpler to detect and require smaller pattern sizes to attain enough energy. Conversely, detecting small impact sizes necessitates bigger samples. The instrument incorporates impact measurement estimates into the pattern measurement calculation to make sure that the examine is satisfactorily powered to detect the anticipated enchancment.

  • Components Influencing Energy Calculation

    A number of components are essential within the technique of this calculation and embrace, statistical significance stage (alpha), the impact measurement, and the variability throughout the inhabitants of samples being thought-about. A lower in any of those measures might require an adjustment to pattern measurement, usually necessitating bigger portions to yield extra dependable knowledge for the advance course of to be measured extra precisely.

The instrument permits course of enchancment professionals to quantify the connection between pattern measurement, impact measurement, and statistical energy. By rigorously contemplating these components, initiatives might be designed to maximise the probability of detecting significant enhancements, minimizing the danger of drawing incorrect conclusions and optimizing useful resource allocation inside Six Sigma initiatives.

2. Confidence Stage

Confidence stage represents the specified diploma of certainty that the outcomes obtained from a pattern precisely replicate the traits of the whole inhabitants. Inside the framework of Six Sigma, deciding on an acceptable confidence stage is essential for making certain the reliability and validity of course of enchancment efforts. It instantly influences the willpower, with increased confidence ranges usually requiring bigger samples to attain the specified stage of precision.

  • Definition and Interpretation

    Confidence stage is expressed as a share, indicating the proportion of occasions that the calculated confidence interval would include the true inhabitants parameter. A 95% confidence stage, for instance, means that if the sampling course of had been repeated a number of occasions, 95% of the ensuing confidence intervals would come with the true inhabitants imply. In course of enchancment, which means that one might be 95% assured that the calculated enchancment based mostly on the pattern displays the precise enchancment throughout the whole course of. It’s essential to interpret the choice rigorously because it serves as a elementary consider making certain the end result of a enterprise enterprise is profitable.

  • Influence on Pattern Dimension Necessities

    The upper the specified confidence stage, the bigger the pattern measurement required. This relationship stems from the necessity to cut back the margin of error, which represents the vary inside which the true inhabitants parameter is prone to fall. Rising the arrogance stage narrows the margin of error, thereby requiring a extra consultant pattern from the inhabitants. The instrument quantifies this relationship, permitting course of enchancment groups to steadiness the necessity for a excessive confidence stage with sensible constraints on knowledge assortment assets. An instance of the usage of confidence stage, in addition to its affect on pattern measurement necessities, contains the necessity to have a pattern to be bigger if one is attempting to find out how a demographic of kids might have been affected by a specific situation.

  • Relationship to Alpha Threat

    Confidence stage is inversely associated to the alpha danger (), which is the chance of constructing a Sort I error (rejecting a real null speculation). The method is: Confidence Stage = 1 – . In speculation testing, a smaller alpha danger corresponds to the next confidence stage. This interrelation is vital in Six Sigma, the place minimizing each Sort I and Sort II errors is important for making knowledgeable selections about course of enhancements. This interrelation is vital in making certain Sort I errors don’t happen when confidence stage is being thought-about. Sort I errors, or false positives, have to be rigorously managed and addressed to make sure correct calculations.

  • Sensible Concerns for Choice

    Deciding on the suitable confidence stage requires a cautious consideration of the context of the method enchancment undertaking and the potential penalties of constructing an incorrect resolution. In conditions the place errors may have vital monetary or operational impacts, the next confidence stage could also be warranted, even when it requires a bigger pattern measurement. Conversely, in much less essential conditions, a decrease confidence stage could also be acceptable to scale back knowledge assortment prices and time. The instrument offers a way to evaluate trade-offs between confidence stage, pattern measurement, and danger tolerance. Nonetheless, the ultimate choice ought to nonetheless keep in mind sensible concerns as these might function the final word deciding issue.

The number of a confidence stage is a essential resolution in course of enchancment initiatives. The instrument facilitates a data-driven method to this resolution, enabling groups to steadiness the necessity for statistical rigor with sensible constraints. A correctly chosen confidence stage ensures that conclusions drawn from pattern knowledge are dependable and that course of enchancment efforts are based mostly on a stable basis of statistical proof. The mixing of confidence stage into this instrument’s calculations offers a complete framework for making knowledgeable selections about pattern measurement and statistical energy in Six Sigma initiatives.

3. Margin of Error

Margin of error quantifies the uncertainty related to estimating a inhabitants parameter based mostly on a pattern. In course of enchancment initiatives, together with these using Six Sigma methodologies, managing and minimizing the margin of error is important for making certain the accuracy and reliability of conclusions drawn from pattern knowledge. It has a direct impact on pattern measurement.

  • Definition and Interpretation

    The margin of error represents the vary inside which the true inhabitants parameter is prone to fall, given a specified confidence stage. It’s usually expressed as a plus or minus share. For instance, a margin of error of 5% signifies that the pattern estimate is prone to be inside 5 share factors of the true inhabitants worth. A slender margin of error signifies a extra exact estimate, enhancing the credibility of course of enchancment findings. In follow, that is helpful for evaluating knowledge accuracy specifically Six Sigma initiatives.

  • Influence on Pattern Dimension Calculation

    The specified margin of error instantly influences the amount of knowledge required. Smaller margins of error necessitate bigger pattern sizes, as a bigger pattern offers a extra consultant image of the general inhabitants. Conversely, a bigger acceptable margin of error permits for smaller pattern sizes, lowering knowledge assortment efforts. The instrument permits course of enchancment groups to quantitatively assess the connection between margin of error and pattern measurement, facilitating knowledgeable selections about knowledge assortment methods. The usage of calculations permits companies to manage prices, in addition to receive knowledge in a well timed method.

  • Relationship to Confidence Stage and Commonplace Deviation

    Margin of error is intrinsically linked to each the arrogance stage and the usual deviation of the pattern. A better confidence stage or a bigger customary deviation will lead to a wider margin of error, until the pattern measurement is elevated to compensate. The instrument incorporates these variables into its calculation, offering a complete evaluation of the interaction between confidence stage, customary deviation, and margin of error within the context of course of enchancment. A change in both would require the instrument to recalibrate, however offers companies with a level of accuracy that won’t have been current in any other case.

  • Sensible Implications for Course of Enchancment

    The number of an acceptable margin of error has vital implications for the effectiveness of course of enchancment efforts. A too-large margin of error might result in overlooking real course of enhancements, whereas a too-small margin of error might lead to extreme knowledge assortment prices. Course of enchancment groups should rigorously think about the context of the undertaking, the potential penalties of constructing an incorrect resolution, and the accessible assets when figuring out the suitable margin of error. The instrument aids on this decision-making course of by quantifying the trade-offs between precision, pattern measurement, and price.

Cautious administration of the margin of error is important for drawing correct conclusions from pattern knowledge and maximizing the affect of course of enchancment initiatives. By understanding the connection between the instrument, the margin of error, confidence stage, and customary deviation, course of enchancment groups could make knowledgeable selections about pattern measurement and knowledge assortment methods, in the end resulting in more practical and environment friendly course of enhancements.

4. Course of Variability

Course of variability, inherent in all manufacturing and repair operations, is a essential issue influencing pattern measurement willpower in Six Sigma initiatives. Understanding and quantifying this variability is important for calculating the suitable variety of knowledge factors required to attain statistically vital outcomes. The instrument accounts for course of variation to supply dependable estimates for course of enchancment efforts.

  • Quantifying Variation with Commonplace Deviation

    Commonplace deviation is a generally used statistical measure of course of variation. A better customary deviation signifies higher variability throughout the course of, necessitating a bigger pattern measurement to precisely estimate inhabitants parameters. Within the context, an elevated customary deviation requires a recalculation to keep away from underestimating the information necessities for a undertaking. Actual-world examples embrace the variation in manufacturing tolerances for machined elements or the fluctuation in name dealing with occasions at a customer support middle. These examples instantly affect the precision of statistical inferences and the effectiveness of course of enhancements.

  • Influence on Statistical Energy

    Course of variability instantly impacts the statistical energy of a examine. Excessive variability reduces the flexibility to detect significant variations between course of states (e.g., earlier than and after an enchancment intervention). Consequently, bigger samples are wanted to attain the specified stage of statistical energy. For example, if trying to scale back defects in a course of with excessive inherent variability, a bigger pattern is required to confidently determine a statistically vital discount. It ensures course of enchancment groups have the required info to make knowledgeable selections.

  • Stratification to Cut back Variability

    Stratification includes dividing the inhabitants into subgroups based mostly on components that affect course of variation. By analyzing knowledge inside every stratum, the general variability might be diminished, probably resulting in smaller pattern measurement necessities. An instance could be separating manufacturing knowledge by shift or machine to account for variations in efficiency. Stratification enhances the precision of estimates and optimizes useful resource allocation in knowledge assortment.

  • Measurement System Evaluation (MSA)

    Earlier than calculating acceptable pattern measurement, it’s essential to evaluate the variability launched by the measurement system itself. MSA methods, resembling Gage R&R research, quantify the measurement error, which have to be accounted for in figuring out pattern measurement necessities. If the measurement system is very variable, a bigger pattern will likely be wanted to differentiate between true course of variation and measurement error. This step ensures that course of enchancment efforts are targeted on addressing precise course of points reasonably than measurement artifacts.

In conclusion, course of variability is a key determinant of pattern measurement. By precisely quantifying and accounting for course of variation, and by using methods resembling stratification and MSA, the instrument facilitates the calculation of acceptable pattern sizes. The result is maximized effectivity and reliability of Six Sigma initiatives.

5. Inhabitants Dimension

Inhabitants measurement, representing the full variety of gadgets or observations throughout the scope of research, instantly influences pattern measurement willpower. The affect of inhabitants measurement on calculations varies based mostly on the pattern measurement relative to inhabitants measurement. In situations involving a big inhabitants, its impact on the calculation diminishes considerably. Nonetheless, with smaller populations, its impact turns into extra pronounced and necessitates particular changes. This connection underscores the significance of precisely assessing the inhabitants measurement earlier than deploying the pattern measurement estimation instrument.

When the pattern constitutes a notable share of the inhabitants, making use of a finite inhabitants correction issue is essential. This issue adjusts the usual error of the pattern imply, accounting for the diminished variability encountered when sampling a considerable portion of the inhabitants. For instance, think about a top quality management course of inspecting a batch of fifty gadgets, the place a pattern of 20 is drawn. In such situations, neglecting the inhabitants measurement in calculations would result in an overestimation of the required pattern measurement and probably inflate testing prices. Conversely, for processes involving thousands and thousands of models, as in steady manufacturing, inhabitants measurement turns into practically inconsequential within the estimation.

The connection between inhabitants measurement and pattern necessities just isn’t at all times linear. Because the pattern measurement approaches a bigger share of the inhabitants, the incremental advantage of including extra samples diminishes. Understanding these nuances is significant for balancing statistical accuracy with operational effectivity. The instrument’s correct software requires a radical understanding of inhabitants traits and the right implementation of the suitable statistical changes, significantly when working with comparatively small populations. In abstract, the inhabitants measurement serves as a vital context for efficient software, requiring cautious consideration to make sure that estimates are each statistically legitimate and virtually possible.

6. Speculation Testing

Speculation testing varieties a cornerstone of statistical validation inside Six Sigma methodologies, establishing a structured framework for verifying course of enhancements. The process employs pattern knowledge to judge claims relating to inhabitants parameters, usually involving a null speculation, asserting no impact or distinction, and another speculation, positing the presence of an impact or distinction. Pattern knowledge, obtained utilizing the “six sigma pattern calculator” to find out the suitable amount, is then subjected to statistical checks to establish whether or not ample proof exists to reject the null speculation in favor of the choice.

The “six sigma pattern calculator” instantly influences the reliability and validity of speculation testing. An inadequately sized pattern, as decided by an improper software of the “six sigma pattern calculator,” might result in inadequate statistical energy, growing the danger of failing to detect a real impact (Sort II error). Conversely, an excessively massive pattern might amplify the detection of statistically vital however virtually irrelevant variations. For example, in evaluating a brand new manufacturing course of designed to scale back defects, the “six sigma pattern calculator” helps specify the variety of models to pattern to confidently assess whether or not the defect charge is considerably decrease than the present course of. The result of the speculation take a look at, whether or not rejecting or failing to reject the null speculation, guides essential decision-making in Six Sigma initiatives.

Challenges in successfully integrating speculation testing inside Six Sigma initiatives usually come up from misinterpreting p-values, neglecting assumptions of statistical checks, or failing to account for a number of comparisons. Making certain correct interpretation and software of speculation testing ideas is paramount for deriving significant insights from knowledge. This understanding informs course of enchancment selections. Correct software of each speculation testing and the “six sigma pattern calculator” results in data-driven decision-making. Finally, the reliability of Six Sigma initiatives are improved, which ensures sturdy validation of course of enhancements.

7. Useful resource Optimization

Efficient allocation of assets is a main goal in any course of enchancment initiative. Using a structured method to find out knowledge necessities instantly helps this goal by stopping each over-sampling and under-sampling, every of which carries distinct financial and operational implications.

  • Minimizing Knowledge Assortment Prices

    Knowledge assortment might be resource-intensive, involving labor, gear, and time. Calculating acceptable pattern sizes ensures that knowledge assortment efforts usually are not extreme, thereby lowering pointless prices. An instance features a manufacturing facility the place every knowledge level requires damaging testing; exact calculation minimizes the variety of models destroyed, conserving helpful stock. Miscalculating the pattern measurement might inadvertently result in extra testing that has no added worth.

  • Decreasing Analytical Overhead

    Analyzing massive datasets requires computational assets, statistical experience, and time. By figuring out the minimal knowledge required, the analytical workload is optimized, releasing up assets for different essential duties. For example, in a name middle analyzing customer support metrics, appropriately sized samples streamline the evaluation course of, enabling quicker identification of key efficiency drivers and areas for enchancment. Correct sizing promotes general productiveness.

  • Enhancing Undertaking Timelines

    Extreme knowledge assortment extends undertaking timelines and delays implementation of course of enhancements. Exactly calculated pattern sizes expedite the information assortment part, enabling faster evaluation and implementation of corrective actions. A hospital implementing a brand new affected person care protocol, for instance, can speed up the adoption of the protocol by making certain that the analysis part is accomplished effectively, thereby minimizing disruptions to affected person care.

  • Enhancing Determination-Making Effectivity

    Underneath-sampling can result in inaccurate conclusions and ineffective course of enhancements. This end result has monetary and operational penalties. By calculating the suitable pattern measurement, initiatives improve the probability of constructing knowledgeable selections, avoiding pricey errors. For instance, a monetary establishment assessing the effectiveness of a fraud detection system should guarantee ample knowledge is collected to precisely consider the system’s efficiency. A well-executed sizing calculation contributes to environment friendly decision-making and minimized dangers.

The flexibility to find out acceptable pattern sizes instantly helps useful resource optimization inside Six Sigma initiatives. By avoiding the pitfalls of over- and under-sampling, course of enchancment groups can maximize the effectivity of knowledge assortment, evaluation, and decision-making, resulting in more practical and sustainable enhancements. The right number of these measurement helps monetary and operational effectivity.

8. Threat Mitigation

Statistical evaluation, important to course of enchancment methodologies, inherently includes uncertainty. Managing and mitigating dangers related to incorrect inferences drawn from pattern knowledge is essential. Correct amount calculation performs a pivotal function in lowering these dangers, thereby bolstering the reliability and robustness of Six Sigma initiatives.

  • Minimizing Sort I Errors (False Positives)

    Sort I error, rejecting a real null speculation, can result in pointless course of changes and wasted assets. A correctly calculated amount helps management the chance of committing this error. For instance, implementing a brand new advertising and marketing marketing campaign based mostly on a flawed pattern evaluation may result in vital monetary losses if the marketing campaign proves ineffective. Correct sizing diminishes the probability of constructing such errors.

  • Mitigating Sort II Errors (False Negatives)

    Failing to detect an actual impact (Sort II error) can lead to missed alternatives for enchancment. This case is especially detrimental when enhancements are carried out and never seen via the usage of a “six sigma pattern calculator”. For example, overlooking a real enchancment in manufacturing effectivity attributable to inadequate knowledge might perpetuate suboptimal efficiency. An acceptable amount will increase the chance of detecting true results, thereby lowering the danger of missed alternatives.

  • Decreasing the Influence of Outliers

    Outliers, excessive values within the dataset, can skew outcomes and result in misguided conclusions. A sufficiently massive amount helps to dilute the affect of outliers, offering a extra sturdy estimate of inhabitants parameters. Contemplate analyzing buyer satisfaction scores, the place a couple of extraordinarily detrimental scores may distort the common. Ample sizing minimizes the affect of those outliers.

  • Enhancing the Generalizability of Outcomes

    The flexibility to extrapolate findings from a pattern to the broader inhabitants is important for course of enchancment efforts. Precisely calculated sizes improve the representativeness of the pattern, enhancing the generalizability of the outcomes and the arrogance in making use of these outcomes to the whole inhabitants. In a medical trial assessing a brand new drug, a consultant pattern is essential for making certain that the findings might be confidently utilized to the goal inhabitants.

The strategic software of amount calculation inside Six Sigma initiatives instantly addresses varied types of danger related to statistical inference. By minimizing the probability of Sort I and Sort II errors, mitigating the affect of outliers, and enhancing the generalizability of outcomes, these calculations contribute to extra sturdy, dependable, and defensible course of enchancment initiatives. Mitigating dangers with a “six sigma pattern calculator” additionally helps enterprise selections.

Often Requested Questions About Six Sigma Pattern Calculation

The next addresses frequent inquiries relating to the willpower of knowledge necessities inside Six Sigma methodologies. It clarifies the underlying ideas and sensible functions of the method.

Query 1: Why is exact willpower essential in Six Sigma initiatives?

Correct calculation is important for making certain that the collected knowledge is each ample and related for drawing statistically legitimate conclusions about course of efficiency. An inadequately sized pattern might result in the acceptance of false negatives (failing to detect precise course of enhancements), whereas an excessively massive pattern wastes assets and delays undertaking completion.

Query 2: What are the important thing components influencing the calculated amount?

A number of components decide the required amount, together with the specified confidence stage, the suitable margin of error, the estimated course of variability (usually measured by customary deviation), and the anticipated impact measurement of the method enchancment. Inhabitants measurement turns into related when sampling a major proportion of a finite inhabitants.

Query 3: How does confidence stage affect the calculation?

Confidence stage displays the diploma of certainty that the outcomes obtained from the pattern precisely symbolize the whole inhabitants. Increased confidence ranges necessitate bigger samples to scale back the danger of errors in estimating inhabitants parameters.

Query 4: What’s the function of statistical energy on this context?

Statistical energy is the chance {that a} speculation take a look at will accurately determine a real impact. Reaching enough energy is essential for making certain that carried out modifications genuinely enhance the method. Increased energy necessities usually necessitate bigger samples.

Query 5: How does course of variability have an effect on the end result of calculating pattern sizes?

Better course of variability, as measured by customary deviation, necessitates bigger pattern sizes to precisely estimate inhabitants parameters. Increased variability will increase the uncertainty related to the pattern imply, requiring extra knowledge to attain the specified stage of precision.

Query 6: What are the results of utilizing an incorrect amount in speculation testing?

Utilizing an incorrect amount in speculation testing can result in Sort I errors (false positives) or Sort II errors (false negatives). These errors can lead to incorrect course of changes or missed alternatives for course of enchancment, respectively.

The proper software permits for the optimization of assets, minimizes the danger of drawing incorrect conclusions, and enhances the general effectiveness of Six Sigma initiatives.

The following dialogue will delve into case research illustrating the sensible software of this idea in numerous Six Sigma initiatives.

Ideas for Efficient Software

This part offers important steering for optimizing utilization inside course of enchancment initiatives. It emphasizes the significance of cautious planning and execution to make sure dependable and actionable outcomes.

Tip 1: Clearly Outline Targets: The objectives of the evaluation have to be exactly articulated earlier than utilizing this to find out knowledge wants. A well-defined goal ensures that the calculation is aligned with the undertaking’s supposed outcomes.

Tip 2: Precisely Estimate Course of Variability: Estimating course of variability, usually via customary deviation, is essential. Historic knowledge or pilot research can present helpful insights into the extent of variability throughout the course of. Inaccurate variability estimates will result in unreliable outcomes.

Tip 3: Choose Applicable Confidence Ranges: The selection of confidence stage ought to replicate the criticality of the choices based mostly on the information. Increased-stakes selections warrant increased confidence ranges, requiring bigger portions.

Tip 4: Decide Acceptable Margin of Error: The margin of error represents the specified stage of precision within the estimates. A smaller acceptable margin of error necessitates a bigger pattern, balancing precision with the price of knowledge assortment.

Tip 5: Account for Inhabitants Dimension: When coping with finite populations, significantly when the pattern represents a major proportion of the inhabitants, the finite inhabitants correction issue have to be utilized to keep away from overestimating knowledge wants.

Tip 6: Validate Assumptions: All statistical calculations depend on sure assumptions in regards to the knowledge. Confirm that these assumptions, resembling normality, are fairly happy earlier than deciphering the outcomes. Violations of assumptions can compromise the validity of the calculations.

Tip 7: Pilot Testing for Refinement: Earlier than committing to full-scale knowledge assortment, think about conducting a pilot take a look at to refine estimates of course of variability and assess the feasibility of the information assortment course of. This step will help keep away from pricey errors afterward.

By adhering to those suggestions, practitioners can improve the accuracy and reliability of calculations, resulting in more practical and data-driven course of enchancment initiatives.

The subsequent part presents real-world case research that show the sensible software of those ideas in numerous course of enchancment settings.

Conclusion

This exploration has underscored the essential function of six sigma pattern calculator in course of enchancment. Its software instantly impacts the accuracy, reliability, and effectivity of Six Sigma initiatives. The introduced ideas, components, and suggestions are instrumental in making certain the suitable software of this system throughout numerous situations. A complete understanding of the statistical underpinnings and sensible concerns is paramount for deriving significant insights and attaining sustainable enhancements.

The efficient employment of six sigma pattern calculator stays an important factor for organizations striving for data-driven decision-making and steady enchancment. Rigorous software of those practices facilitates optimized useful resource allocation, mitigated dangers, and enhanced confidence in course of enchancment initiatives. Continued adherence to statistically sound methodologies is essential for attaining organizational excellence and sustaining a aggressive benefit in an evolving panorama.