Two Ways to Collect Data:
Response Variable/ outcome variable: outcome of the research study.
Explanatory variable: variable that may explain or cause differences in a response
Confounding variable (KEY WORD:
Hypothesis Testing — Two Independent Samples
Independent samples: Two samples are independent if the sample values
selected from one population are not related to or matched (paired)with
the sample values selected from the other population.
Look at the four datasets and the descriptive statistics
Descriptive Statistics: C1, 02, C3, C4
Variable Mean StDev Variance Minimum Median Maximum
5.00 0.00 0.00 5.00 5.00 5.00
5.00 1.58 2.50 3.00 5.00 7.00
5.00 9.19 84.50 —10.00 7.00 15.0
Hypothesis Testing — One Sample
° Hypothesis is a claim or a statement about a property of a population.
° Hypothesis test (or test of signiﬁcance) is a standard procedure for
testing a claim about a property of a population.
Components of formal hypothes
Paired Sample Hypothesis testing
0 Paired samples —> If the random samples on which :7)“ and 7;
are based are selected dependently of one another, then the
samples are called paired samples.
l) The sample data consists of matched pairs.
Sampling: The tendency for samples to differ from the corresponding population in some systematic
Selection bias/undercoverage results from systematic exclusion of some part of the population.
Measurement/ response bias occurs when the method of obse
Provides methods to help us study a population based on data collected from a sample.
Is the science of collecting, analyzing and drawing conclusions from data.
Studies variability in data.
There are two branches in statistics:
1 Descriptive s
.The Average American/Canadian eats about 11.9Ibs of cereal
.The Average American/Canadian drinks about 600 soda’s per
.More People use blue toothbrushes then red ones.
.According to a 1995 survey, 7 out of 10 British d
Central Limit Theorem and Sampling Distribution of f
The random variable X has a distribution (which may or may not be
normal) with mean [u and standard deviation 0
Simple random samples of size n are selected from the population.
(All possible s
November 26th, 2013
Computer Assignment 5
Check for Normality
Probability-plot shows a linear trend
Results from ANOVA
Results for GROUP = Hospital 1
Results for GROUP = Hospital 2
Conﬁdence Intervals and sample size
Point estimate: A point estimate is a single value used to
approximate a population parameter.
Sample mean )7 is the best point estimate of the population
A conﬁdence interval (or interval estimate) is the inter