Statistics Power Point Presentation - Please have an in-depth background in Statistics Introduction You have learned lots about doing statistical analyses. It is time to work without a net. For the course project, you will address some questions that in

Prisoner Populations Example author

Research question:

Have prison populations increased significantly?

Hypothesis:

The prison population is growing, so the 2015 prisoner amounts will be greater than the 2000 prisoner amounts.

I can establish a need for more prison guards to be recruited and hired.

Literature review

 A systematic review of randomized controlled trials of

interventions to improve the health of persons during

imprisonment and in the year after release

(Kouyoumdjian, McIsaac, Liauw, Green, Karachiwalla, Siu,

...Hwang, 2015)

 A Hero’s Welcome? Exploring the Prevalence and Problems

of Military Veterans in the Arrestee Population (White,

Mulvey, Fox, & Choate, 2012)

Data collection

Data from 2000 US prison populations

and 2015 prison populations by state

Had all states and District of Columbia

represented

Used a census sample as all population

data was available

http://data.sagepub.com/sagestats/

Descriptive statistics:

Prisoners in 2015

Mean 26606.74

Standard Error 4453.26959

Median 18597.5

Mode #N/A

Standard Deviation 31489.3713

Sample Variance 991580503

Kurtosis 8.66533957

Skewness 2.70936979

Range 162159

Minimum 1750

Maximum 163909

Sum 1330337

Count 50

Prisoners in 2000

Mean 24065.2885

Standard Error 4464.09442

Median 14919

Mode 14919

Standard

Deviation 32191.0426

Sample Variance 1036263226

Kurtosis 11.3617562

Skewness 3.15629496

Range 161925

Minimum 1076

Maximum 163001

Sum 1251395

Count 52

Graphical representations

Box and Whisker plots

Methodology

Quantitative data, at the ratio level

Independent t -test (t test: two sample assuming equal variances)

Looking for a statistically significant increase in the number of prisoners

 1 –tailed test due to the hypothesized increase

Results:

t-Test: Two-Sample Assuming Equal Variances

Variable 1 Variable 2

Mean 26449.69608 24065.28846

Variance 973006695.7 1036263226

Observations 51 52

Pooled Variance 1004948112

Hypothesized

Mean Difference 0

df 101

t Stat 0.381660161

P(T<=t) one-tail 0.351757613

t Critical one-tail 1.66008063

P(T<=t) two-tail 0.703515227

t Critical two-tail 1.983731003

6 step hypothesis test:

1. Ho: μ2000≥ μ 2015

Ha: μ2000< μ2015

2. α = .05

3. the one-tailed p-value = .35

4. p-value > α

5. Fail to reject the null

6. At the 5% significance level, there is not enough information to state that the population mean for 2015 is greater than the population mean for 2000.

Conclusions & Discussion

 The prison population is not increasing

 The mean is decreasing, but is not significantly significant

 Any difference in the sample mean results may not be inferred to the population

 The results show that there are individual states and/or prisons that are increasing, but the general population is at approximately the same value in the population

 There is not an increased need for prison personnel in the population; politics may not have any real affect on how many people are imprisoned in the USA in any given year.