EXPLAIN IT CLEARLY! Throughout the quarter, we have claimed that random assignme

Question

EXPLAIN IT CLEARLY!

Throughout the quarter, we have claimed that random assignment will serve to create equivalent groups. This question asks you to think about how random assignment actually works with a small group of participants.

Use the data in the table below. You are welcome to copy and paste the numbers into an Excel spreadsheet.

This table describes 20 participants who differ on a number of variables. If you randomly assigned them to either an "Experimental" condition or a "Control" condition, would the two groups, on average, be equal?

Start at the top of the list. Flip a fair coin for each participant. If the coin lands on heads, assign that participant to the Experimental Condition. If the coin lands on tails, assign that participant to the Control Condition.

QUESTION 1:
List the participant numbers that are in each condition.

QUESTION 2:
What is the sample size of each group?

QUESTION 3:
Calculate and report the means and standard deviations of Age, IQ and Self-esteem for both of the groups.
(You are welcome to use Excel to calculate the means and standard deviations. Use the formulas =average and =stdev)

QUESTION 4:
Do the groups seem similar? Did random assignment result in the pesky individual differences being equally placed in the two groups? For these participants, Age has a very small range - your two groups are likely to be very similar. On the other hand, IQ has a very large range - your two groups might be quite different.

Participant Age IQ Self-esteem 1 19 145 42 2 19 73 48 3 21 86 30 4 27 108 36 5 18 85 38 6 24 141 42 7 22 91 28 8 25 100 39 9 23 93 40 10 21 103 36 11 28 93 45 12 21 107 44 13 26 94 43 14 25 114 35 15 24 78 40 16 25 104 45 17 25 119 42 18 27 81 41 19 21 136 38 20 23 97 42

Explanation / Answer

Q-1)

We are assigning first 10 observations to group 1 and the last 10 to group 2

Q-2)

10 in each group

Q-3 & 4)

Participant Age IQ Self-esteem Group 1 19 145 42 1 2 19 73 48 1 3 21 86 30 1 4 27 108 36 1 5 18 85 38 1 6 24 141 42 1 7 22 91 28 1 8 25 100 39 1 Group 1_Age Group 1_IQ Group 1_Self-esteem 9 23 93 40 1 Mean SD Mean SD Mean SD 10 21 103 36 1 21.9 2.8848262 102.5 23.561975 37.9 5.85851707 11 28 93 45 2 12 21 107 44 2 13 26 94 43 2 14 25 114 35 2 15 24 78 40 2 16 25 104 45 2 17 25 119 42 2 18 27 81 41 2 Group 2_Age Group_2_IQ Group_2_Self-esteem 19 21 136 38 2 Mean SD Mean SD Mean SD 20 23 97 42 2 24.5 2.32139805 102.3 17.6512511 41.5 3.1710496

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