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## Statistics and probability

### Course: Statistics and probability > Unit 1

Lesson 2: Two-way tables- Two-way frequency tables and Venn diagrams
- Two-way frequency tables
- Read two-way frequency tables
- Create two-way frequency tables
- Two-way relative frequency tables
- Create two-way relative frequency tables
- Analyze two-way frequency tables
- Interpreting two-way tables
- Interpret two-way tables
- Categorical data example
- Analyzing trends in categorical data
- Trends in categorical data
- Two-way relative frequency tables and associations
- Two-way tables review

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# Categorical data example

We can explore the relationship between two categorical variables with two-way tables to see if there is an association between the variables. In this example, we see if data from a sample suggests an associate between video games and violence. Created by Sal Khan.

## Want to join the conversation?

- Is the faction who plays video games is 4 or 5?(7 votes)
- there are basically 5 kids who play the games and 4 of them didn't get into a fight(11 votes)

- I didn't understand what exactly you want to convey from this video. You took a small sample and analysed according to that and concluded what??(4 votes)
- I believe the main point of this video was an introduction on how to categorize and organize data into a frequency table.(9 votes)

- Why don't all the fractions add up to 1?(2 votes)
- This is a row-relative frequency table. The fractions add up to 1 in each row.(8 votes)

- Playing does cause violent Behavior if they have anger issues but without anger issue it cause anger issues or not. So it's pretty much the issues of the person that matter.

Am I right or not(2 votes) - Here's a tip: Only read the graph in the way it's structured. If it's read as a column graph read it in a column way, not in rows. Otherwise it would be wrong as the population wouldn't apply to both. If the question has a statement that says something that has the opposite structure to that of the actual graph then it's wrong because the graph should be interpreted in the right way.(2 votes)
- is this true or is it mostly fake stuff i am lost(2 votes)
- Are they playing Battlefield or Call of Duty?(2 votes)
- Why are these logical questions, not computational questions(2 votes)
- There is a mistake at2:10in the video. You only count 3 students as being in a fight; however, there are 4 students that have been in a fight in the data.(1 vote)
- It's actually correct because yes there are 4 students that have been in a fight. But we are interested in students who have been in a fight but also who do not play violent video games and there are 3 such students. I hope its clear to you.(2 votes)

- Why did he change from 1/15 to 1/5 and from 4/15 to 4/5? Anyone can explain to me, thanks.(1 vote)
- He simplified the fraction 3/15 by dividing the numerator and denominator by 3. 3 goes into 3 -> 1 time. 3 goes into 15 -> 5 times. The resulting fraction is 1/5.

The second fraction was 12/15. It was also reduced by a factor of 3. 3 goes into 12 -> 4 times. 3 goes into 15 -> 5 times. That gives us 4/5.(2 votes)

## Video transcript

Lucio wants to test whether
playing violent video games makes people more violent. He asks his friends whether
they play violent video games and whether they have been
in a fight in the last month. He recorded the results
in the table shown below. Fill in the table to show
the fraction of each group of students who have
been in a fight. Then decide whether
there is an association between violent video games
and getting in a fight amongst Lucio's friends. So let's see what
they're doing here. So students who
play video games-- fractions who have been in a
fight, fraction who haven't. Students who don't play
violent video games-- fraction who have been in a
fight, fraction who haven't. So let's answer the
first part of this. Students who play
violent video games. So let's look at those students. So the students who play
violent video games-- it looks like Ellen plays
violent video games. Actually, let me just focus on
the data that we care about. So Ellen. So let's look at all the people
who play violent video games. So let's see. This column is
violent video games. So we have a yes here. So actually, we have both
of these right over here. And then we have down here. And then that's all of them. There's 1, 2, 3, 4, 5 people
who play violent video games. Now what fraction of them
have been in a fight? Well, it looks like 1 out of
the 5 have been in a fight. The rest of them have
not been in a fight. So we could say 1/5--
let's just write that down. So 1/5 have been in a fight. Fraction who haven't-- 4/5. So that's all these other nos. They play violent
video games, but they haven't been in a fight. 1, 2, 3, 4-- 4/5. So students who don't
play violent video games. Well, that's everyone else. And let's see how many
data points that is. That is 1, 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12, 13, 14, 15. So there's a total
of 15 students. And how many of them
have been in a fight? So let's see. We have 1. And then let's see,
1, and 2, and 3. So 3 out of the 15
have been in a fight. So 3 out of 15 is the
same thing as 1 out of 5. Those are equivalent fractions. And then the
fraction who haven't? Well, that's just going
to be everyone else. That's going to be 12
out of 15 or 4 out of 5. So based on Lucio's data-- and
this wasn't a huge sample size, obviously. He only found 5 kids who were
playing violent video games. And 1 of them had
gotten into a fight. So this isn't a
super rigorous study. But at least based
on his data, if we're trying to decide whether
there's an association between violent games
and getting into a fight amongst Lucio's friends, it
doesn't seem like there is. It seems like relatively,
whether or not they play violent video
games or not, 1/5 of them have been in a fight
in the last month. So it really doesn't
seem any difference. If this number was, I
don't know, 4/5, or 5/5, or all of them, then I'd say,
hey, even with Lucio's fairly small sample, I
would say, hey, maybe there is some type of
a strong association between playing violent
video games and fighting. But here you really
don't see any difference.