Frequency table

[Jerry Scherer]

On my spreadsheet page, I have the scores of 30 students on a test, listed in no particular order. I am able to display a histogram showing the test scores in intervals of 5 units. If you hover over any of the bars, it indicates the number of students who scored in that interval. For example, [75,80) 4 points, indicates 4 students with scores in the 75-80 interval.

1.       What is the command that I could use on a calculator or spreadsheet page that produces that result? The command frequency(score,75, 80) returned an error message. However, frequency(score, 80)  returned {24,6}, the number 24 students who scored 80 or less and 6 students who scored higher.

 

2.       Also, how can I create a new frequency table on a spreadsheet page that illustrates the frequency of scores in intervals of 5 units ( 0-5,6-10,11-15,…, 96-100)?

 

Thanks,

 

Jerry

 

[Marc Garneau]

Frequency will return a list of frequencies in intervals specified by a bins list.

What you want is the countIf function, which has syntax:

countIf(list, criteria)

For your particular case, you can count the frequency in an interval by specifying the interval in the criteria using ? as a variable.  For example, for the interval (75, 80], enter:

countIf(score, 75<?<=80)

For your second question, the frequency command is probably the best bet:

frequency(marks, seq(5*i,i,1,19))

This will return the frequency for the intervals (-inf, 5], (5, 10], ... (90, 95], (95, inf)

A similar thing could be done using countIf:

seq(countIf(marks,5*i<?<=5*i+5),i,0,19)

Note though that this has (0, 5] as the first interval, so it's excluding 0.  This is so it includes the multiple of 5 at the right end of each interval.  Given that there aren't any negative scores, you could simply change the 0 to -1 to get the interval (-5, 0].

Marc Garneau

On 2012-01-23, at 4:41 PM, Jerry Scherer wrote:

On my spreadsheet page, I have the scores of 30 students on a test, listed in no particular order. I am able to display a histogram showing the test scores in intervals of 5 units. If you hover over any of the bars, it indicates the number of students who scored in that interval. For example, [75,80) 4 points, indicates 4 students with scores in the 75-80 interval.

1.       What is the command that I could use on a calculator or spreadsheet page that produces that result? The command frequency(score,75, 80)returned an error message. However, frequency(score, 80)  returned {24,6}, the number 24 students who scored 80 or less and 6 students who scored higher.

 

2.       Also, how can I create a new frequency table on a spreadsheet page that illustrates the frequency of scores in intervals of 5 units ( 0-5,6-10,11-15,…, 96-100)?

 

Thanks,

 

Jerry

 

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[Jerry Scherer]

Thanks Marc. It worked. See you in Chicago.

Jerry

[Dennis Donovan]

Is it odd that given the same bins, frequency() and the histogram on a Data & Statistics page count differently?

Example: If we're talking test scores and all grades are from 60 - 100, bins with width 5, a histogram will give counts on [60,65), [65,70), etc.  But frequency(tests, seq(5*k,k,12,19) will give counts on ?<=60, (60,65], (65,70], etc.

---

From: Marc Garneau <pi...@telus.net>
To: tins...@googlegroups.com
Sent: Monday, January 23, 2012 8:30 PM

Subject: Re: [tinspire] Frequency table