Sample mean: x bar
Descriptive- organizing,summarizing, presenting data
Inferential – making conclusions and inferences about The data
Cumaltive relative frequency
Box plot: q1 – mean –q3
A fitness Center is interested in the mean amount of time a client exercises in the Center each week.
population: all clients in fitness center
sample: group of these clients
parameter: population mean amount of time clients Exercise in center each week
statistic: sample mean amount of time clients exercise In center each week
variable: X=the amount of time one client exercises in The center each week
data: values for X (4 hours, 6 hours, 10 hours, etc.)
number of Tickets sold to a concert Quantitative discrete, 100 percent of body fat Quantitative continuous, 10% favorite baseball team
The t distribution is flatter in the middle and the Tails are wider.
The more degrees of freedom we have, the closer we get To the actual number.
The difference in the hypothesis test is that the Critical region changes and the normal curve uses +/- 1.96.
Increase the variability of the scores :
Increases denominator and t is closer to zero
Increase the number of scores in the sample :
Decreases the Sm in the denominator, and increases t.
Increase the difference between the sample mean and the Population mean:
Increases numerator and increases t.
Sample standard deviation is the average distance Of all of the data from the mean in the population. The standard error is the Average distance of all the samples of the size of the data (n) in the Population mean.
5. - Ho µ phys. Ed test=12
H1 µ phys. Ed test≠12
Two tailed, a=.05
Df =25-1= 24 Critical region: ±2.064
T = 15-12/29/√25= 1.67
We fail to reject the null hypothesis Because there is no significant effect of the P.E programs on pushup scores, on Average, students who are in P.E programs do not perform better. M=15, SD=1.67
The heights of The 430 National Basketball Association players were listed on team rosters at The start of the 2005–2006 season. The heights of basketball players have an Approximate normal distribution with mean µ = 79 inches and a standard Deviation σ = 3.89 inches. For each of the following heights, calculate the Z-score and interpret it using complete sentences.
77 inches z= 77-79/3.89 in. = -2/3.89= -2/3.89 = -0.5141The height of 77 in. Is 0.5141 standard deviations Below the mean. 77 inches is shorter than average.
The 90th percentile for recovery times is?7.99-5.3/2.1=2.69+2.1=1.2801 à 0.39973+.5= 0.89973 à .90
In national use, a vocabulary test is Known to have a mean score of 68 and a standard deviation of 13. A class of 19 Students takes the test and has a mean score of 65. What is the probability That the 19 students will obtain the mean of 65 or higher?
For a sample of n = 25 scores, what is the Probability that the sample mean will be within 5 points of the population Mean? In other words, what is p(95 < < 105)?
Z = (M - μ) / √(σ2 / n)
Z For 95 à95-100/225/√25 =-5/3=-1.66667
Z for 100 à 105-100/20/√25 = 5/3 =1.66667
Law of large numbers - if You take samples of larger and larger size from any population, then the mean x ¯ of the sample tends to get closer and closer to μ
Sampling distribution- if You draw random samples of size n, the distribution of the sample means, that Is called the sampling distribution of the mean. The sampling distribution of The mean approaches a normal distribution as n, the sample size, increases.
Central limit theorem- the Larger the sample size, the more normal the distribution will be.
Standard error-the standard Deviation of the distribution of the sample means
formulas: z=x-u/o z=x-u/o/sq root of n
t=x-u/s/sq root two sample independent t: t=(x1-x2)-(u1-u2)/s(x1-x2)
formula for dependent measures: t=ed/sq root nED squared-(ED)squared/n-1
Houcomf=u not comf
t=x1-x2 ... =-3.27
reject null, look at means shorter height more comfy
- 1 sample measured two times depends on T more control and size of group (advantages of dependent t test)
we use chi square or nonparametric stats when data comes as frequencies, it is measured at nominal or categorical level
prego not prego total -
clown 33 60 93 93(51)/186=25.5 --- 33-25.5squared/35.5=2.21 add and compare
no clown 18 75 93
total : 51 135 186