Question

True or false.

A simple random sample is not just a sample where every population member has an equal chance of being drawn.

Answer 1

@Directrix i think its false but i just wanna make sure

Answer 2

What do you think?... Do you have any ideas?

Answer 3

ohh.

Answer 4

In a random sample of a population, what makes the sample random is that every member of the population has an equal chance of being selected.

This question has an odd wording to it. Let's think.

Answer 5

here, this link may help you http://en.wikipedia.org/wiki/Simple_random_sample

Answer 6

@Directrix yea my textbook definition says a sample drawn so that every member of the population has an equal probability of being selected into the sample and every population subset of size n has an equal probability of being selected in the sample

Answer 7

Avoid Wikipedia for research.

Same here:

Simple Random Samples
The simplest type of random sample is a simple random sample, often called an SRS. Moore and McCabe define a simple random sample as follows:

"A simple random sample (SRS) of size n consists of n individuals from the population chosen in such a way that every set of n individuals has an equal chance to be the sample actually selected."

https://www.ma.utexas.edu/users/mks/statmistakes/SRS.html

Answer 8

yea, the only thing that got me questioning if it was true was it saying its not just as in theres another factor

Answer 9

Well, what about that "not?" Would that mean that the SRS could be something more, I wonder.

Answer 10

yea I'm not quite sure

Answer 11

What answer are you thinking if you had to write something now?

Answer 12

false

Answer 13

False is what I think.

Answer 14

ok thanks :) @perl can i get your opinion please?

Answer 15

I just looked at your textbook definition.

Answer 16

This is a poorly written question. Probably not written by a math person.

Answer 17

oh ok, but its still false isn't it?

Answer 18

maybe because of that extra condition you mentioned above

Answer 19

Your textbook definition has two criteria for a random sample of size n.
criteria 1: the sample is drawn such that every member of the population has an equal probability of being selected
criteria 2: every population subset of size n has an equal probability of being selected in the sample

Answer 20

So a simple random sample is not just a sample where every population member has an equal chance of being drawn, you also need every subset of size n has equal probability of being selected.

Answer 21

oh that makes it true then

Answer 22

this is also confirmed by wikipedia
"a simple random sample is a subset of individuals (a sample) chosen from a larger set (a population). `Each individual is chosen randomly and entirely by chance, such that each individual has the same probability of being chosen at any stage during the sampling process, `and `each subset of k individuals has the same probability of being chosen for the sample as any other subset of k individuals.`

Answer 23

it looks like two conditions

Answer 24

ideally , we can look at examples of random samples which only satisfy one condition and compare that to samples that satisfy both conditions. thats usually better than an abstract definition :)

Answer 25

so its true then?

Answer 26

yes

Answer 27

ok thanks so much!