The boxplot below is based on the birth weights of infants with severe idiopathic respiratory distress syndrome (SIRDS). The mode is the element of the data set that occurs most frequently. Counting up in the data as we did before, There are 6 data values of $15, so Values 1 to 6 are $15 thousand, The next 8 data values are $20, so Values 7 to (6+8)=14 are $20 thousand, The next 11 data values are $25, so Values 15 to (14+11)=25 are $25 thousand, The next 17 data values are $30, so Values 26 to (25+17)=42 are $30 thousand. The LibreTexts libraries arePowered by NICE CXone Expertand are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. The mode is the data value that occurs most often. Range describes the span of the data, or how far apart the biggest and smallest values are. To better illuminate the differences, well have to turn to more sophisticated measures of variation. A central angle is an angle whose vertex is the center of a circle central angle is equal to the degree measure of its intercepted arc. After we identify the middle, it is helpful to understand how spread out that data may be. Extending off the last example, suppose a new family moves into the neighborhood example that has a household income of $5 million ($5000 thousand). D 4.) Range is defined as the difference between the largest and smallest values. Statistics Measures of Variation Worksheet 1 - ) 1.) The most elementary measure of variation is range. Entire Library Printable Worksheets Games Guided Lessons Lesson Plans. size: = 5 range: 10 = 26 mean: = 5.2 median: 3 variance: 2 = 20.2 standard deviation: = 4.49 CV =86% Pearson's Skew: 1.47 Skew direction: 8.) It does not describe the variation among the variables. Some of the worksheets for this concept are Measures of central tendency mean median and mode examples, Practice lesson 29 using measures of center and, Center and spread of data, Math 7th grade geometry crossword 3 name, Math mammoth grade 6 b worktext sample, Resources to support student learning during school, 10 measures of variation, Working The range is 10, yet this data set is quite different from Section B. Free trial available at KutaSoftware.com. Find the standard deviation of the prices. Mean - The average of all the values in the data set is known as mean. Some of the worksheets displayed are Measures of central tendency mean median and mode examples, Name date the measure of center of data sets, 10 measures of variation, Measures of central tendency work, Measures of central tendency name mcas work 1, Measures of central tendency variability, Center and spread of data, How do we choose which Another common measure of variability is known as standard deviation, which measures how far each of the measurements in a data set are from the mean value. After students complete the acti, Range, Quartiles and Interquartile RangeMeasures of Variation No Prep Interactive Notebook Pages and ActivitiesCommon Core Standard: 6.SP.A.2, 6.SP.A.3, 6.SP.B.5cIncluded in this product: No Prep Interactive Notebook Pages:*Range Notes (2 per page)*Quartile Brainstorming Activity (4 per page)*Quartile Notes (2 per page)*Quartiles Practice (2 per page)*Interquartile Range Notes (2 per page)*Measures of Variation Practice (2 per page)*Measures of Variation Investigation Activity (mini book) *Measu, This Probability and Statistics Unit Bundle includes guided notes, homework assignments, two quizzes, a study guide and a unit test that cover the following topics: The Fundamental Counting Principle Permutations Combinations Theoretical Probability Probability of Independent and Dependent Events Conditional Probability The Binomial Theorem Binomial Probability Measures of Center: Mean, Median, Mode Measures of Variation: Mean Absolute Deviation, Standard Deviation, and Variance Norma, These 24 task cards use 6 sets of data in which students will find the mean, median, Q1, Q3, and the IQR. To find the mode, count how many times each value appears in the data set. Examining all the measures of central tendency provides a good description of the data set. There are eleven total parts to the project. There are three measures of central tendency; mean, median, and mode. Quizzes with auto-grading, and real-time student data. Now it's time to start to see how the mean and median are affected +. Two-Tailed Test Uses, Formula & Examples | What is a Two-Tailed Test? In the previous example, that means about 25% of households have income between $40 thousand and $50 thousand. How can data not have numbers? of the data. If the number of data values is even, there is no one middle value, so we find the mean of the two middle values (values \(N/2\) and \(N/2 + 1\) ). The median of a set of data is the value in the middle when the data is in order. The mean is the average of all the values. What Is a Unit Rate? Get your students engaged with this set of 20 task cards! Let's look at another example. This divides the data into quarters; 25% of the data is between the minimum and Q1, 25% is between Q1 and the median, 25% is between the median and Q3, and 25% is between Q3 and the maximum value. The second part of this section describes measures of variation. Get Started. )225 14.) The graph depicts the data of median incomes. What are points-squared? This is often not a critical aspect of a form of interpretation but is helpful when preparing to visualize and organize the data to explain to others. To print this group, add it to a test. These statistics worksheets will have students use data pools and learn to calculate measures of center and the degree to which the data differs. {eq}\frac{\sum_{1}^n{}\left | x_{i}-x\bar{} \right |}{n} {/eq}. Calculating the mean by hand could get tricky if we try to type in all 100 values: \[\dfrac{\overset{6 \text { terms }}{\overbrace{15+\cdots 15}}\; + \overset{8 \text { terms }}{\overbrace{20+\cdots 20}} + \overset{11 \text { terms }}{\overbrace{25+\cdots 25}} + \cdots}{100} \nonumber \]. Spread describes the variation of the data. The midrange is the best measure of center if the distribution is u shaped. Displaying all worksheets related to - Measures Of Variation. Informally assess the degree of visual overlap of two numerical data distributions with similar variabilities, measuring the difference between the centers by expressing it as a multiple of a measure of variability. B 5.) If there's an even number of measurements, choose the number that falls right between the two middle values. Standard deviation - A figure that represents how far each number is from the mean is known as standard deviation. Variability helps you to understand the variation in a sets of numbers. So in our example, we would have 50/10 = 5 if section D represents a population and 50/9 = about 5.56 if section D represents a sample. 2. Part Three: Box-And-Whisker Plot. When the data forms a U-shaped symmetrical distribution, the midrange is the preferred measure of center. A sample of numerical data is gathered from a population to determine what is usual in the population. I'll fix it ASAP. If the values are present far from the mean, the standard deviation is high. Using two real-world data sets, students will calculate the measures of center and variation without an outlier then with an outlier. Displaying all worksheets related to - Measures Of Variation 6th Grade. This can be completed by students as a whole-group, as a center, or individually. There may be one or more clusters in any given data set. Since 100 is an even number, we need to find the mean of the middle two data values - the 50th and 51st data values. The mean is the total sum divided by the total frequencies. What is the mean number of touchdown passes thrown in the NFL in the 2000 season? Also, learn more about these statistical values and when each should be. These include the mean absolute deviation, the median absolute deviation, the variance, and the standard deviation. Box plots are particularly useful for comparing data from two populations. The mean rounded to the nearest hundredth is 57.11. 2. The sum of the largest and smallest is 125. All three of these sets of data have a mean of 5 and median of 5, yet the sets of scores are clearly quite different. The instructions are easy to follow for you to make a copy of the quiz to your Google Drive. {eq}\frac{\sum_{1}^n{}\left | x_{i}-x\widetilde{} \right |}{n} {/eq}. The midrange is the average of the smallest and largest values in the data set. All other trademarks and copyrights are the property of their respective owners. 75% 10. )576 11. The box plot of service times for two fast-food restaurants is shown below. Then the lower half is the same as in Example 25 (its median is 61). Step 1: Calculate the measure of center/variation for each set of data. 50 Questions. For the 8 female sample, the median is 65, the minimum is 59, and the maximum is 70, so the 5- number summary would be: 59, 61, 65, 68, 70. That depends upon your opinions about luck 25% of customers at store 2 had to wait between 5.7 and 9.6 minutes. Betsy has a Ph.D. in biomedical engineering from the University of Memphis, M.S. Part IV: Written Description. A 27-page packet full of math games and activities builds on algebra, measurement, geometry, fractional, and graphing skills. FTCE Elementary Education K-6 (060): Practice & Study Guide, Mass and Volume: Formulas, Unit Conversion & Practice Problems, Psychological Research & Experimental Design, All Teacher Certification Test Prep Courses, About the FTCE Elementary Education K-6 Test, The Reading Process & Comprehension Strategies, Representations of Information in the Classroom, Understanding & Teaching the Writing Process, Social Science Instruction & Comprehension, Cultural Contributions & Technological Developments in History, World Civilizations & Historical Timelines, Tools & Resources for Science Instruction, Scientific Data Interpretation & Analysis, Life Science Classification & Life Cycles, Selecting Appropriate Measurement Units to Solve Problems, Selecting Measures of Center & Variability for Data, Distance Formulas: Calculations & Examples, Praxis Biology and General Science: Practice and Study Guide, Praxis Biology: Content Knowledge (5236) Prep, ILTS Social Science - Geography (245): Test Practice and Study Guide, ILTS Social Science - Political Science (247): Test Practice and Study Guide, Introduction to Political Science: Certificate Program, DSST General Anthropology: Study Guide & Test Prep, UExcel Political Science: Study Guide & Test Prep, NY Regents Exam - Global History and Geography: Help and Review, NY Regents Exam - US History and Government: Help and Review, UExcel Workplace Communications with Computers: Study Guide & Test Prep, Effective Communication in the Workplace: Certificate Program, Effective Communication in the Workplace: Help and Review, Central Tendency: Measures, Definition & Examples, Using Mean, Median, and Mode for Assessment, Central Tendency: Dot Plots, Histograms & Box Plots, Measures of Central Tendency: Definitions & Practice, Measures of Central Tendency: Definition, Equations & Examples, Impacts of Personal Crimes on Direct & Indirect Victims, Hate Crimes: Motivations & Effects on the Community, Assault & Robbery: Extent, Impacts & Motivations, Family Violence: Immediate Consequences & Long-Term Impacts, Victimization in the Workplace: Explanation & Trends, What is Cyberbullying? While store 2 had a slightly shorter median service time (2.1 minutes vs. 2.3 minutes), store 2 is less consistent, with a wider spread of the data. The variance can help determine which measure of center is the best. The worksheet comes with an explanation of how a student would determine which is the better measure so there is no prep for the teacher! Standard deviation will be zero only if all the data values are equal and will get larger as the data spreads out. Standard Deviation. There are several measures of variation. The mode is the data value that occurs the most. Making sense of this figures is one of the more challenging aspect of data interpretation and it often done by looking at some key metrics that indicate the nature of any data set. Using the data from section D (Example \(\PageIndex{10}\)), we could compute for each data value the difference between the data value and the mean: We would like to get an idea of the "average" deviation from the mean, but if we find the average of the values in the second column, the negative and positive values cancel each other out, resulting in the average deviation of 0 (this will always happen). Measures of Center and Variation with Outliers by Math with Mrs Stephens 8 $1.50 PDF Students will explore how an outlier affects the measures of center (mean, median, and mode) and measure of variation (range). If we are unsure whether the data set is a sample or a population, we will usually assume it is a sample, and we will round answers to one more decimal place than the original data as we have done above. A measure of center, also known as a measure of central tendency, is a statistic that describes the data set by identifying the center. Four measures of center are. To find the median, begin by listing the data in order from smallest to largest, or largest to smallest. There are three measures of central tendency; mean, median, and mode. 37, 33, 33, 32, 29, 28, 28, 23, 22, 22, 22, 21, 21, 21, 20, 20, 19, 19, 18, 18, 18, 18, 16, 15, 14, 14, 14, 12, 12, 9, 6. a. It is read as . Title: document1 Worksheet. The score with the frequency of 7 is the midpoint 28 of the interval 26-30. Find and create gamified quizzes, lessons, presentations, and flashcards for students, employees, and everyone else. | How to Find Distribution of Data, Statistical Questions | Statistical vs. Non-Statistical Questions Examples, Constant of Proportionality Graph | How to Find the Constant. Lesson 11.1 Measures of Center and Variation Essential Question How can you describe the variation of a data set? What is the denominator in the calculation of population standard deviation for a data set with . The range is a single number. Let us return now to our original household income data. Central Tendency and Dispersion Worksheet Students will identify the requested information from the data set provided. Outliers that are far from the mean can change the mean a lot, so that it doesn't reflect the midpoint of the data. 9 filtered results. Part III: Creating 3 Graphs; a histogram, a dot plot and a box-n-whisker plot. This can be found by rounding \(N/2\) up to the next whole number. Worksheets are Measures of central tendency mean median and mode examples, Name date the measure of center of data sets, 10 measures of variation, Measures of central tendency work, Measures of central tendency name mcas work 1, Measures of central tendency variability, Center and spread of data, How do we choose which measures of center and | 73 Worksheets are 10 measures of variation, Introductory statistics lectures measures of variation, Grade levelcourse math 6 and math 7, 13 shape of data distributions, Math mammoth grade 6 b worktext sample, Center and spread of data, 6th grade unit 1, Grade 6 statistics and probabilty 7 weeks unit 5. Anytime you want to use your data to determine which item is the most popular, the mode is a good choice. Although there was only one mode in this case, it's possible to have more than one if there were two or more data points that occurred the same number of times. Some very low or very high salaries will skew the data and the middle value, the median, will provide a better description of the data. Introduction to Measurement. Plus, get practice tests, quizzes, and personalized coaching to help you Measures of Central Tendency and Variation Cover sheet, Measures of Central Tendency Cover Sheet, Measures of Variation Cover Sheet The median absolute deviation is the average distance the values are from the median. Variance "Average Deviation" Showing top 8 worksheets in the category - Measures Of Center. MMeasures of Centereasures of Center A measure of center is a measure that represents the center, or typical value, of a data set. The shape of the dot plot suggests that the out lier 11 may be affecting these measures of center. This can be reduced to be printed for individual student binders/notebooks or enlarged to be printed as a poster or anchor chart. A measure of variation is a statistic that is known as a measure of spread or dispersion. Notes and assignment on the measures of center (mean, median, and mode) and variation (range and standard deviation). Since there are 31 data values, an odd number, the median will be the middle number, the 16th data value (31/2 = 15.5, round up to 16, leaving 15 values below and 15 above). Measures of Center and Variation Deliverable 07 Worksheet Scenario You are currently working at NCLEX Memorial Hospital in the Infectious Diseases Unit. In section A, everyone had the same score; in section B half the class got no points and the other half got a perfect score, assuming this was a 10-point quiz. EXPLORATION 1 Describing the Variation of Data Work with a partner. 413 lessons The mean is the average of all the values. The median is the data value in the center of the data when the values are listed in order. In situations like this, where one value is much bigger or smaller than most other value in the data, there is a better measure of center than the mean. The decision of the best measure of center depends on several factors. Definitions of each term are included. For section B, the range is 10 since 10 0 = 10. Returning to our quiz score data. Four of the sets are whole numbers, while the other 2 include fractions and decimals. Let's calculate the range of each team. Good question. An outlier can affect the mean. As a member, you'll also get unlimited access to over 88,000 The measures for variance are standard deviation and range. 8 pictures about 30 fire safety merit badge worksheet | education template :. Browse Measures of Variation Educational Resources. Step 1: Calculate the measure of center/variation for each set of data. In this article, we will look at 4 measures of variation. You must also be able to identify a given. We need to be careful with the word "average" as it means different things to different people in different contexts. Any QR scanner will work! The number of pages that Carolyn wrote in her journal each day from Monday to Friday is shown below: 9, 8, 12, 6, 10. Let's say that in a data set, which represents 12 students borrowing books from the library. Sort by. Start for free now! The lessons included are: 1) Central tendency2) Trimmed mean3) Weighted mean4) Measures of variation5) Z score6) Percentile/quartile7) Outliers8) Box plots9) Distribution ShapeThis product will get updated as I modify during my yearly curriculum u, Your students are going to LOVE this interactive Statistics Project!You can choose either paper/pencil or digital formats for this project.Students can work individually, in pairs or in small groups.There are 5 parts to this project: Part I: Creating a Statistical Question Part II: Collecting Data & Determining the Measures of Center, Variation & 5 number summary. Median - The number that falls in the exact center of the given data is known as the median. One important aspect of a distribution is where its center is located. For section C, the range is 2 since 6 4 = 2. Measures of center are used in statistics to describe a set of data by providing a value that is typical. A few important characteristics: Standard deviation is rather complicated. As you can see, it takes multiple steps to calculate the standard deviation of a dataset. For normally distributed data, the median and mean will be very similar, so either one can be used; however, using the mean is the more common approach. 3. Measures of Central Tendency & Variability Videos and lessons with examples and solutions to help High School students learn how to use measures of center and measures of variability for numerical data from random samples to draw informal comparative inferences about two populations. The mathematical formula for a set of n data values represented by {eq}x_{i} {/eq} is. Measures of Variation . If there are outliers and the data doesn't appear to be normally distributed, then the median is a better choice than the mean because it more accurately reflects the true midpoint of your data. Students will notice that the mean is mostly affected by an outlier. You may see slightly different explanations in other resources. The QR codes are color coded so you will see which cards are the same sets of data. There are four measures of center: Mean Median. It also helps in comparing the statistics of your data with other information that you may have available or have collected. Find the median price. Describing Distributions in Histograms. The mode is the best measure of center if the interest is for the answer that occurs the most. The mean absolute deviation is the average distance the values are from the mean. Worksheets are 10 measures of variation, . This is the main reason the median, not the mean, is used to represent certain data, such as the average household income or home price. We can see in the table that the minimum income is $15 thousand, and the maximum is $50 thousand. 1. Measures Of Variation Worksheet (FAVS.PICS) - Web measures of variation in statistics are ways to describe the distribution or dispersion of data. Students are exposed to relevant vocabularies such as average, middle, most frequent, and read about how mean, median, and mode is used in bas. Suppose we have measured 9 females and their heights (in inches), sorted from smallest to largest are: The lower half, {59, 60, 62, 64}, has the median of 61, and the higher half, {67, 69, 70, 72}, has the median of 69.5. Jeanne Rast has taught Mathematics in grades 7-12 and college for over 30 years. The worksheet for reasoning about center and spread consists of having the students make predictions about the amount of the time the students in their class spend: traveling to school, exercising in a week, communicating with their parents, eating, on the internet, studying, and on their cell phones. Standard deviation has the same unit as the original data. Continuing our counting from earlier, The next 19 data values are $35, so Values 43 to (42+19)=61 are $35 thousand, The next 20 data values are $40, so Values 61 to (61+20)=81 are $40 thousand. Four measures of center are the mean, median, midrange, and mode. - Facts & Statistics, Capital Crime: Definition, Rates & Statistics, Working Scholars Bringing Tuition-Free College to the Community. In this case, you'd keep track of all of the orders and then determine the mode (the most commonly ordered flavor). Variability - Variability is defined as how much a group of data is spread. In addition to measures of center, measures of variation are also used to describe data. Variability is the measure of how dispersed from the center, the values that we have collected are. The three measures of center are the mean, the median, and the mode. However,really impressive app!. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. In our vehicle color survey, we collected the data. There are also PDF versions included!Lesson Objectives:-Describe data using measures of, Measures of Center and Variation *Aligned to CCSS 7.SP3 & 7.SP.4, 7th Grade Statistics and Probability Unit Resource Bundle, Range, Quartiles & Measures of Variation Interactive Notebook, Probability and Statistics (Algebra 2 Curriculum - Unit 11) | All Things Algebra, Algebra 2 Curriculum | All Things Algebra, Measures of Variation Task Cards with QR Codes, Measures of Center and Variation Lesson | Warm-Up | Notes | Homework, Algebra 2 Curriculum | Lessons | Warm-Up | Guided Notes | Assessments, Measures of Center and Variation Self Checking Task Cards, Find the Error - Data and Graphs with Central Tendency and Variation, Analyzing Data (Measures of Center and Variation) Anchor Chart, 6th Grade Math (& More) Anchor Charts *BUNDLE*, Measures of Center and Variation Quiz for Google Forms - 6.SP.3, 6th Grade Quiz Bundle (Entire Year) for Google Forms - Distance Learning, Statistics - Interactive Measures of Variation & Center Activity, Measures of Variation Task Cards (40 Task Cards), Measures of Central Tendency and Variation Checklists, Statistics Unit: Measures of Center and Spread (Full Year). For Teachers 9th - 10th. At store 1, 75% of customers were served within 2.9 minutes, while at store 2, 75% of customers were served within 5.7 minutes. language variation in sociolinguistics slideshare; 202272 measures of center and variation worksheet . Dividing by 31, the number of data values, we get 634/31 = 20.4516. $140 $160 $160 $165 $180 $220 $235 $240 $250 $260 $280 $285, $285 $285 $290 $300 $300 $305 $310 $310 $315 $315 $320 $320, $330 $340 $345 $350 $355 $360 $360 $380 $395 $420 $460 $460. If we didnt already know that, we could find it by adding the frequencies. The 5-number summary combines the first and third quartile with the minimum, median, and maximum values. What is the Constant of Proportionality? The 25th data value is $25 thousand, and the 26th data value is $30 thousand, so Q1 will be the mean of these: (25 + 30)/2 = $27.5 thousand. Included in this product: Describing Data Using Mean, Median, Mode, and Range. The mean of a set of data is the sum of the data values divided by the number of values. Students will an. Notice that the new neighbor did not affect the median in this case. The most common measure of variation, or spread, is the standard deviation. The measures of center combined with measures of variation can give a comprehensive understanding of a population. Mode is the best measure to use when data is non-numerical, or in any situation where you want to know the most popular option among a group. Divide by \(n\), the number of data values, if the data represents a whole population; divide by \(n - 1\) if the data is from a sample. Median - The number that falls in the exact center of the given data is known as the median. {eq}\frac{\sum_{1}^{n}\left ( x_{i}-x\bar{} \right)^{2}}{n} {/eq}. For Teachers 2nd - 5th. To unlock this lesson you must be a Study.com Member. Showing top 8 worksheets in the category - Measures Of Center And Variabillity. TPT empowers educators to teach at their best. The median is the number that falls in the exact center of all the measurements, while the mode is the number that occurs most frequently. Students are given cues to help them remember how to find each measure, along with an example of each. The standard deviation is commonly used to describe many data distributions. Data is presented as a stem and leaf plot, a raw data set, a box and whiskers plot, a table and as a dot plot. 6th Grade Math Curriculum Unit 7 {Buy the full curriculum HERE}This unit includes five multi-day lessons that the following skills :Measures of Center and VariationLine Plots and Stem and Leaf PlotsFrequency Tables and HistogramsBox and Whisker PlotsCharacteristics of Data DisplaysIncluded in this resource: Google Forms versions of the asses, If you're looking for a no-prep exit ticket, bellringer, or digital center for your budding mathematicians, then look no further!Your students will love playing Statistics: Two Truths and a Lie while addressing standard 6.SP.B.5.C in this interactive drag, drop, and record activity!This Google Slides assignment is also great for teachers - easy to grade at-a-glance with a visual answer key, and is a great opportunity for computer-based centers in your physical classroom!What's included in your, Practice Makes Perfect! With these task cards, your students will be able to practice key mathematical concepts.The product includes:40 Measures of Variation Task CardsAnswer KeyRecording Sheets (4 versions)This types of problems your students will solveFind the range, Interquartile Range (IQR), 1st quartile, median, and 3rd quartile from a set of data. Young mathematicians participate in math games collaboratively, promoting teamwork and skills practice. A comparison of the data sets with different standard deviations. One important factor is the spread, or variation, of the data. You may have guessed that the second quartile is the same as the median, since the median is the value so that 50% of the data values are below it. It is often the first step in any form of data evaluation. Lesson Plans . Measures of Center: Mean, Median, & Mode Measures of Variation: Range, Variance & Standard Deviation Measures of Position: Obtain the Five number summary Use Pearson's Index of Skewness to determine if the distribution is skewed. If we add in the new neighbor with a $5 million household income, how does the median change? The mean is the best measure of center if the data is normally distributed. If we graph our household data, the $5 million data value is so far out to the right that the mean has to adjust up to keep things in balance. Susan decides to track the number of books checked out by each student for a month, recording all the data she collects in a table like this: Once Susan has compiled her data, how can she determine the typical number of books checked out by the children in her class and summarize and present this information? when finding population variance, you divide Skip to document Ask an Expert Sign inRegister Sign inRegister Home Ask an ExpertNew Adding this to our sample, our mean is now: \[\dfrac{15 \cdot 6+20 \cdot 8+25 \cdot 11+30 \cdot 17+35 \cdot 19+40 \cdot 20+45 \cdot 12+50 \cdot 7+5000 \cdot 1}{101}=\frac{8390}{101}=83.069 \nonumber \]. If there is an even number of values, average the two values in the middle and that is the median. If the data has outliers, the median is the best measure of center.
Healing Blanket Prayer, Francesco Becchetti Net Worth, Keith Zlomsowitch Net Worth, 6 Week Old Pitbull Puppies For Sale, Richard Fontaine Obituary, Articles M