VARIABILITY in a data set means: — Values differ from one another.Variability means the data values are DIFFERENT — some are higher, some lower. Understanding variability is central to statistics.
"How many pets do families in our school own?" — Why is this statistical? — Different families have different numbers of pets.Different families own different numbers of pets — the answers vary. Variability makes it statistical.
Which is the BEST statistical question for investigating TV watching habits? — How many hours per day do people in your neighborhood watch TV?.Different people watch different amounts of TV daily — variability exists. This is the best statistical question.
A class collects data on shoe sizes. This is statistical because: — Different students have different shoe sizes.Different students have different shoe sizes — variability is present. Analyzing the distribution is meaningful.
Which aspect makes a question statistical vs. non-statistical? — Whether the answer varies across subjects or samples.The key is VARIABILITY. If different subjects/samples give different answers, it is statistical. If one answer exists for all, it is not.
A researcher wants to know about sleep patterns of American teens. The RIGHT type of question is: — Statistical: How many hours do American teens sleep per night?.Different American teens sleep different amounts — variability exists. This is a proper statistical question for research.
You ask 30 students "How many books did you read last year?" The data ranges from 0 to 25. This variability suggests: — Students read different amounts — a natural variation to analyze.A range of 0 to 25 shows natural human VARIABILITY in reading habits — exactly what makes this a valid statistical question!
Same data: 2, 4, 4, 4, 5, 5, 7, 9. Median = ? — 4.5.Ordered (8 values): 2,4,4,[4,5],5,7,9. Median = average of 4th and 5th = (4+5)/2 = 4.5.
An outlier is a value FAR from the others. Which measure is MOST affected by an outlier? — Mean.Mean is MOST affected by outliers — it uses every value in its calculation. Median is resistant to outliers.
Salaries: $40K, $45K, $42K, $48K, $200K. Which is a better "typical" salary: mean or median? — Median.The $200K outlier pulls the mean way up. The MEDIAN ($45K) better represents the typical salary, unaffected by the extreme value.
Data with an even number of values: 3, 5, 8, 10. Median = ? — 6.5.No single middle value. Average the two middle: (5+8)/2 = 6.5.
A data set has no repeated values. What is the mode? — There is no mode.Mode = most frequent. If no value repeats, there is NO MODE for this data set.
Five test scores: 82, 91, 78, 92, 88. For a 6th test, what score is needed for a mean of 87? — 89.Target sum = 87×6 = 522. Current sum = 431. Need: 522−431 = 91.
Which measure tells you the SPREAD of data? — Range.Range = Max − Min tells you how SPREAD OUT the data is — how wide the data extends.
An OUTLIER in a box plot appears as: — An isolated dot beyond the whiskers.Outliers appear as isolated dots (or asterisks) beyond the whiskers of a box plot.
In a histogram with intervals [10,20), [20,30), [30,40): tallest bar is at [20,30). This means: — Most values fall between 20 and 30.The tallest bar in a histogram means the most data values fall in THAT interval (20-30 in this case).
MAD = 3.5 for a data set with mean 20. What range captures most typical values? — 16.5 to 23.5.Mean ± 1 MAD = 20 ± 3.5 = 16.5 to 23.5. This range is where "typical" values cluster.
When would a DOT PLOT be preferable to a HISTOGRAM? — For small data sets where individual values matter.Dot plots show every individual value — best for SMALL data sets. Histograms are better for large sets where individual values matter less.