Keep Missing Values Different from Zero
Keep recorded zero and unknown separate when you interpret the table.
About 12 minutes, plus any extended practice
Supplied materials
- Paper and pencil; answers may also be spoken or typed.
- All cases, labels, numbers and rules are supplied on this page. No real account, private information or purchase is needed.
Learn the idea
A blank or unknown field does not mean zero. Zero is a recorded quantity; missing means the value was not supplied. Treating missing values as zero changes conclusions. A clear record uses a consistent missing marker and explains it in the key.
Keep recorded zero and unknown separate when you interpret the table. Never fill an unknown answer with zero just to make a table look complete.
Use this supplied case: Count=0. Key: ? means unknown. Interpret the field. Use the details in this example. An adult may read the words aloud. Point, draw or say your answer.
- Follow the worked example one step at a time. Say or draw what happens.
- Keep recorded zero and unknown separate when you interpret the table.
- Say which detail makes the example answer fit. Pick another answer and say why it does not fit.
- Try the question and practice questions. Read the rule again if your answer does not match the explanation.
See the method in action
Count=0. Key: ? means unknown. Interpret the field. The supported answer is Recorded zero. Keep recorded zero and unknown separate when you interpret the table. Never fill an unknown answer with zero just to make a table look complete. A blank or unknown field does not mean zero. The supplied facts, rather than an assumed real-world detail, determine this paper case. Compare the recorded action or value with the stated rule before choosing an answer.
Check your reasoning
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Helpful tips
- Keep recorded zero and unknown separate when you interpret the table.
- Never fill an unknown answer with zero just to make a table look complete.
See the answer and explanation
Recorded positive count
The supplied case states: Count=3. Key: ? means unknown. Interpret the field. Under the stated distinction, this identifies Recorded positive count. A blank or unknown field does not mean zero. Zero is a recorded quantity; missing means the value was not supplied. Treating missing values as zero changes conclusions. A clear record uses a consistent missing marker and explains it in the key. Keep recorded zero and unknown separate when you interpret the table.
Take it further
New field key: blank=unknown. Counts 0 and blank differ:0 is checked empty; blank remains unknown. Do not substitute zero.
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More practice: try new cases
Choose an answer for each problem. Explain your method on paper, then use the feedback to decide what to revisit.
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Check the subject sources
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