Question

9. 3/5 points Previous Answers PagUnderStat9 14.EOC.25. My Notes + Ask Your Teacher Developmental psychologists at a prominent California university conducted a longitudinal study investigating the effect of high levels of curiosity in early childhood on intelligence. The local population of 3-year-olds was screened via a test battery assessing curiosity. Twelve of the 3-year-olds scoring in the upper 90% of this variable were given an IQ test at age 3 and again at age 11. The following IQ scores were obtained. Subject Number IQ (Age 3) 103 102 IQ (Age 11) 116 119 141 154 106 119 136 136 148 139 122 128 104 98 113 (a) Using a = 0.012 tail, what do you conclude? In drawing your conclusion, assume that it is well established that IQ stays relatively constant over these years for individuals with average or below-average levels of curiosity. tobt =

*what is the t obt ?

* Estimate the size of the real effect.
d̂ =

Answer 1

Ans:

	IQ(age 3)	IQ(age 11)	d
1	103	116	13
2	102	119	17
3	125	141	16
4	138	154	16
5	108	106	-2
6	122	119	-3
7	115	136	21
8	112	136	24
9	135	148	13
10	128	139	11
11	104	122	18
12	98	113	15
		d-bar	13.25
		sd	8.1589

Test statistic:

t_obt=(13.25-0)/(8.1589/sqrt(12))

t_obt=5.626

df=12-1=11

critical t value=tinv(0.01,11)=3.106

Reject the null hypothesis and can conclude that there is significant difference in IQ levels.

effect size=(13.25-0)/8.1589=1.62