Univariate Data

NZ Level 5

Number of Observations

Lesson

The number of scores in a data set is also called the total frequency. The number of scores in a data set is simply how many numbers there are written down. For example, if you survey $40$40 people, then you will have $40$40 scores in your data set.

To find the number of scores in a set, we simply have to count all the scores in our set. For example, if we had the numbers $17$17, $19$19 and $22$22 in a data set, we could count the scores and say that the number of scores (or the total frequency) is $3$3 because there are three numbers in the set.

Ms Barnett has just marked a set of homework. The scores she gave were:

$99,26,36,31,2$99,26,36,31,2

How many pieces of homework did Ms Barnett mark?

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Aaron has been recording the number of goals he has scored in soccer matches so far this year.

$1,2,4,2,3,4,2,2,1,3,2$1,2,4,2,3,4,2,2,1,3,2

How many soccer games has Aaron played so far this year?

What is the total number of goals Aaron scored in all matches?

A teacher has marked a set of tests and put the scores of her class into the table below.

Score | Frequency |
---|---|

$26$26 | $13$13 |

$27$27 | $8$8 |

$28$28 | $2$2 |

$29$29 | $19$19 |

$30$30 | $5$5 |

- How many students took the test?

The frequency polygon below shows the scores awarded to a mathletes team during several recent competitions.

How many competitions have the mathletes team taken part in recently?

Plan and conduct surveys and experiments using the statistical enquiry cycle:– determining appropriate variables and measures;– considering sources of variation;– gathering and cleaning data;– using multiple displays, and re-categorising data to find patterns, variations, relationships, and trends in multivariate data sets;– comparing sample distributions visually, using measures of centre, spread, and proportion;– presenting a report of findings