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### Course: Statistics and probability > Unit 1

Lesson 1: Analyzing one categorical variable- Identifying individuals, variables and categorical variables in a data set
- Individuals, variables, and categorical & quantitative data
- Reading pictographs
- Read picture graphs (multi-step problems)
- Reading bar graphs
- Reading bar graphs: Harry Potter
- Creating a bar graph
- Create bar graphs
- Reading bar charts: comparing two sets of data
- Read bar graphs (2-step problems)
- Reading bar charts: putting it together with central tendency
- Reading pie graphs (circle graphs)
- Picture graphs (pictographs) review
- Bar graphs review

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# Reading pictographs

Common sense tells you that a pictograph must be some kind of....picture. Yes! A pictograph is basically a way to represent data with pictures that relate to the data. Let's look at this word problem that asks to interpret a pictograph. Created by Sal Khan and Monterey Institute for Technology and Education.

## Want to join the conversation?

- What do you do when there's half of an object?(157 votes)
- When there's only half an object, it means that only half the "units" are being represented. For example, in this video, half a blood drop would mean 4 people because a whole drop means 8.(92 votes)

- How does "●" symbolise multiplication?(49 votes)
- The Reason Why The Dot Is A Sign Of Multiplication( Simplified Reason) is to avoid confusion between variables.. For example

9 x (X=30)

In This Problem , The problem solvers may get confused with the two X's , so to fix this situation mathematicians have resolved to using a dot as a sign of multiplication . Your Welcome :D(19 votes)

- I know this is not that related to the video but shouldn't there be more o neg because o o neg the common blood type sorry if I have bad grammar I am a fifth grader and I really doubt that no one an will look back at this thing because it is old and I am older do that doesn't matter(6 votes)
- Hi. O is the most common blood type. But most of those are O positive. O negative is rarer. Only about 7 percent of the population have O negative.(6 votes)

- Why do we divide by 2 when there is half an object ?(5 votes)
- Half of a picture tells us that the picture represents half of the value of the regular sized picture. In the video example, if there was half a drop of blood it would represent 4 people, we get this by dividing the regular value of 8 people per drop of blood by 2. If there ever is a quarter or a third of a picture you would also divide to find out what value they were as but you would divide by 4 and 3 to find out the value.(7 votes)

- what to do if a question said one drip = 3 people but there is half a drip(5 votes)
- Hi, you can divide the 3 by 2 which gives 1.5 in this case(4 votes)

- idk, maybe you're good at probability(4 votes)

- How are pictographs used in real life?(3 votes)
- Hey Marvin! Pictographs are useful for visualizing lots of information in an easy way. I took this example from wikipedia's page on pictographs, which pictures the casualties of the accident involving RMS Titanic (Pretty tragic, but pretty accurate too!) http://upload.wikimedia.org/wikipedia/commons/thumb/6/69/Titanic_casualties.svg/512px-Titanic_casualties.svg.png(4 votes)

- What is the age I am supposed to be doing this course at(2 votes)
- i mean, i'm almost a junior in high school and we just started this unit, but I also remember doing this in 6th grade as well.(4 votes)

- i cant understand that picture thing(2 votes)
- It is basically a table, however , instead of numbers showing you the result of a category, there are pictures. These pictures usually have a key, so in the example of the video, one blood drop is equal to 8 people. Let me know if you need further explanation.(2 votes)

- Where would pictographs be used in real life?(2 votes)
- in some jobs you use pictographs, diagrams and tables. Like for example,if you want to work in a company, then you'll have to make a diagram/graph of how much you sell your products in the past 3 months.(1 vote)

## Video transcript

According to the
pictograph below, how many survey respondents
have type O positive blood? How many have O negative blood? So a pictograph is
really just a way of representing
data with pictures that are somehow
related to the data. So in this case, they
gave us little pictures of, I'm assuming, blood
drops right over here. And then they tell us that each
blood drop in this pictograph represents 8 people. So you could kind of view that
as a scale of these graphs. Each of these say 8 people. So, for example, if you say how
many people have A positive? It would be 1, 2, 3,
4, 5, 6, 7 blood drops. But each of those blood
drops represent 8 people, so it would be 56 people
have type A positive. But let's answer
the actual question that they're asking us. How many survey respondents
have type O positive? So this is O, and then
we care about O positive. So we have 1 blood drop, 2, 3. I'm going to do this in
a new, different color. We have 1, 2, 3, 4, 5, 6, 7, 8. So we have 8 drops. I'll put those in quotes because
they're pictures of drops. And then the scale is 8 people. Let me write it this way. Times 8 people per drop. And so 8 times 8-- and
actually even the drops, you could view them
as canceling out if you view them as
units, so drops, drops. 8 times 8 is equal to 64 people. So they could have written
literally the number 64 right over here. 64 people have type
O positive blood. Now let's think about
the O negative case, O negative blood. Well, this is O. And then
within the blood group O, this is O negative. And we have 1 drops, 2 drops. So we have 2 drops
times 8 people per drop. And so 2 times 8, each
of these represent 8. So 8 and then 16, or 2 times
8 is equal to 16 people. So 16 of the survey respondents,
16 have type O negative. 64 have type O positive.