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52 lines
2 KiB
HTML
52 lines
2 KiB
HTML
<div class="book-prose">
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<p>
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Data handling starts with organizing data clearly, choosing suitable charts, and summarizing a
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dataset with averages.
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</p>
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<h2 id="data-tables" class="book-prose__heading">Frequency tables</h2>
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<p>
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A frequency table records each value (or class interval) and how often it appears.
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For grouped data, use class midpoints for estimation.
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</p>
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<h2 id="common-charts" class="book-prose__heading">Common charts</h2>
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<ul>
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<li><strong>Bar chart:</strong> categorical comparisons.</li>
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<li><strong>Histogram:</strong> continuous grouped data (touching bars).</li>
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<li><strong>Line graph:</strong> change over time.</li>
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<li><strong>Pie chart:</strong> part-to-whole proportions.</li>
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<li><strong>Box plot:</strong> spread via quartiles and median.</li>
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</ul>
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<h2 id="mean-median-mode" class="book-prose__heading">Mean, median, and mode</h2>
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<p class="book-formula">\[
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\text{Mean}=\frac{\text{sum of values}}{\text{number of values}}.
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\]</p>
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<p>
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<strong>Median</strong> is middle value when ordered. <strong>Mode</strong> is most frequent value.
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</p>
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<h2 id="weighted-mean" class="book-prose__heading">Mean from frequency table</h2>
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<p class="book-formula">\[
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\bar{x}=\frac{\sum fx}{\sum f}.
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\]</p>
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<p>
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where \(x\) is value (or midpoint), \(f\) is frequency.
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</p>
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<h2 id="which-average" class="book-prose__heading">Choosing an average</h2>
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<ul>
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<li>Use <strong>mean</strong> when data has no extreme outliers.</li>
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<li>Use <strong>median</strong> when distribution is skewed.</li>
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<li>Use <strong>mode</strong> for most common category/value.</li>
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</ul>
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<h2 id="exam-strategy" class="book-prose__heading">Exam strategy</h2>
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<ul>
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<li>Label axes and units clearly on charts.</li>
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<li>Check scale intervals before reading values.</li>
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<li>Order data before finding median and quartiles.</li>
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<li>State if an answer is estimated from grouped data.</li>
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</ul>
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</div>
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