Faulty sensor readings and outliers
Name:
Date:
Class:
A
Quick Questions
Shade in the A or B circle for each question.
1. A classroom temperature sensor logs 21, 22, 22, 23, then -999. What should you do with the -999?
2. Which reading is most likely an outlier in this list of room temperatures: 20, 21, 21, 22, 85?
3. A temperature sensor is placed next to a heater and reads much higher than the other sensors. What could this mean?
4. A sensor logs a reading every minute, but nothing is recorded from 10:05 to 10:20. What is the best explanation to check first?
5. Which statement about outliers is correct?
B
Match the Pairs
Draw a line connecting each item on the left to its match on the right.
| Left column | Right column | |
|---|---|---|
| 1-999 | A=MAX(B2:B50) | |
| 2=IF(OR(B2<-10,B2>50),"Check","OK") | BThe sensor is in the wrong place, so its reading is far from the true air temperature and cannot be trusted | |
| 3A sensor stops working for a while, leaving gaps in the log where readings should be | CThe -999 reading is impossible and was not checked, so it will drag the average far too low | |
| 4Find the highest reading to spot a value that is far from the rest | D=COUNTBLANK(B2:B50) | |
| 5Average temperature = 18, 19, -999, 20 -> use all four readings as they are | EAn impossible temperature reading that usually means the sensor has failed, so check it before use | |
| 6A temperature sensor sits in direct sunlight on a hot car roof, so 58 is taken as the air temperature | FFlags a temperature reading that is impossible or far outside the expected range for checking |
C
Definitions
outlier
D
Fill in the Blanks
Complete each line of code by filling in the missing parts.
1.
=___(B2:B30)
2.
=IF(B2=____,"Check","OK")
3.
=IF(__(B2<-10,B2>50),"Check","OK")
4.
=__________(B2:B30)
5.
=___(B2:B30)
E
Spot the Error
Shade in the letter of the line that contains an error.
Question 1
A
let temp = input.temperature()
B
if (temp = -999) {
C
console.log("Check sensor")
D
}
Question 2
A
let temp = input.temperature
B
if (temp < -50 || temp > 60) {
C
console.log("Faulty")
D
}
Question 3
A
let r = [21, 22, -999, 23]
B
let good = []
C
for (let x of r {
D
if (x > -999) good.push(x)
E
}
Question 4
A
let avg = 21
B
let reading = 95
C
let diff = reading + avg
D
let isOutlier = diff > 20
Question 5
A
Lowest: =MIN(B2:B20)
B
Highest: =MAX(B2:B20)
C
Average: =AVERAGE(B2:B20)
D
Gaps: =COUNT(B2:B20)
Answer Key
Faulty sensor readings and outliers
Section A: Quick Questions
Q1
B — Check it first, because it is impossible and may be a sensor fault
Q2
B — 85
Q3
A — The sensor may be in the wrong place
Q4
A — The sensor may have stopped working for a while
Q5
A — An outlier may be a fault, so check it before you use it
Section B: Match the Pairs
Q1
-999 → An impossible temperature reading that usually means the sensor has failed, so check it before use
Q2
=IF(OR(B2<-10,B2>50),"Check","OK") → Flags a temperature reading that is impossible or far outside the expected range for checking
Q3
A sensor stops working for a while, leaving gaps in the log where readings should be → =COUNTBLANK(B2:B50)
Q4
Find the highest reading to spot a value that is far from the rest → =MAX(B2:B50)
Q5
Average temperature = 18, 19, -999, 20 -> use all four readings as they are → The -999 reading is impossible and was not checked, so it will drag the average far too low
Q6
A temperature sensor sits in direct sunlight on a hot car roof, so 58 is taken as the air temperature → The sensor is in the wrong place, so its reading is far from the true air temperature and cannot be trusted
Section C: Definitions
Q1
outlier — A reading far from the rest or impossible, like -999. It may mean the sensor is faulty or in the wrong place, so check it before you use it.Section D: Fill in the Blanks
Q1
=MIN(B2:B30)Q2
=IF(B2=-999,"Check","OK")Q3
=IF(OR(B2<-10,B2>50),"Check","OK")Q4
=COUNTBLANK(B2:B30)Q5
=MAX(B2:B30)Section E: Spot the Error
Q1
B — A single = assigns a value instead of comparing. To test for the impossible -999 reading, use == (or ===): if (temp == -999).
Q2
A — input.temperature is a function, so it needs brackets to run and give a reading. It should be input.temperature().
Q3
C — The closing bracket is missing from the for loop heading. It should be for (let x of r) { so the loop keeps only readings that are not the -999 fault value.
Q4
C — To see how far a reading is from the rest, subtract the average from it. Adding them gives a meaningless number. It should be reading - avg.
Q5
D — COUNT only counts cells that hold numbers, so it misses the gaps made when a sensor stops. COUNTBLANK counts the empty cells.