research lecture 4 Flashcards
(117 cards)
1
Q
what are methods for organizing and summarizing data
A
descriptive statistics
2
Q
what is a descriptive value for a population called
A
parameter
3
Q
what is a descriptive value for a sample called
A
statistic
4
Q
what is the first task for a researcher after collecting the data
A
organize and simplify the data to get a general overview of the results
5
Q
one method for simplifying and organizing data is to construct a
A
frequency distribution
6
Q
what presents an organized picture of the entire set of scores, and it shows where each individual is located relative to others in the distribution.
A
frequency distribution
7
Q
what is used when a set of scores covers a wide range of values.
A
Grouped frequency distribution
8
Q
Grouped frequency distribution and frequency destruction are frequently displayed as what
A
histograms
9
Q
If the scores in the population are measured on an interval or ratio scale and the N is large, it is customary to present the distribution as a
A
smooth curve
10
Q
the smooth curve emphasizes the fact that the distribution is not showing what
A
the exact frequency for each category
11
Q
how would you like the shape of your data to be
A
symmetrical
12
Q
what shape is when the two sides are close to mirror images of each other…
A
symmetrical
13
Q
what shape is when scores pile up on one side of the distribution, leaving a “tail” of a few extreme values on the other side.
A
skewed
14
Q
scores bunched at low values with the tail pointing to high values ais called what kind of frequency distribution
A
positive skew
15
Q
scores bunched at high values with the tail pointing to low values is called what kind of frequency distribution
A
negative skew
16
Q
what kind of kurtosis is frequency distribution is a higher/ thinner peak
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leptokurtic
17
Q
what kind of kurtis is frequency distribution is a lower/ broader peak
A
platykurtic
18
Q
which kurtosis frequency distribution is hard to get significance and has increase variability
A
platykurtic
19
Q
which kurtosis frequency distribution has better significance and doesn’t have a high variability
A
leptokurtic
20
Q
what is a statistical measure that describes the center of the distribution and represents the entire distribution of scores as a single number.
A
central tendency
21
Q
what are the 3 commonly used techniques from measuring central tendency
A
the mode , median and mean
22
Q
which central tendency is the most frequent score
A
mode
23
Q
which central tendency is have 2 modes called anf having several modes
A
bimodal and multimodal
24
Q
what is defined as the most frequently occurring category or score in the distribution.
A
the mode
25
what is the mode appropriate for
nominal, ordinal, interval, or ratio level data.
26
if teh score in a distribution are listed in order form smallest to largest , what is defined as the midpoint of the list
the median
27
what is the median appropriate for
ordinal, interval, or ratio level data.
28
what is one advantage of the median
that it is relatively unaffected by extreme scores
29
what is a con for the median
doesn’t tell u the significant difference
30
what is the most commonly used measure of central tendency.
the mean
31
Computation of the mean requires scores that are numerical values measured on an…
interval/ratio scale
32
when a distribution contains a few extreme scores (skewed) the mean will be pulled toward the ___
extremes
33
when do you not report the mean
with data from a nominal score or ordinal scale
34
Because the mean, the median, and the mode are all measuring central tendency, the three measures are often ___ related to each other.
systematically
35
in a symmetrical distribution what will always be equal
mean and median
36
in a skewed distribution where will each central tendency be (mean , median and mode)
the mode will be located at the peak
mean is usually closer to the tail
median is in between the mean and mode
37
what serves both as a descriptive measure and as an important component of most inferential statistics
variability
38
what is it called when variability measures the degree to which the scores are spread out or clustered together in a distribution.
descriptive statistic
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what is it called when variability provides a measure of how accurately any individual score or sample represents the entire population.
inferential statistics
40
what does less variability mean
better representation
41
what is the difference when the population variability is small and large
When the population variability is small, all of the scores are clustered close together and any individual score or sample will likely provide a good representation of the entire set.
On the other hand, when variability is large and scores are widely spread, it is easy for one or two extreme scores to give a distorted picture of the general population.
42
what are the 2 ways that variability can be measure with
the range and SD/ variance
43
variability is determined by measuring the ___
distance
44
what is the total distance covered by the distribution, from the highest score to the lowest score.
the range
45
For the data set: 2, 5, 7, 9, 10....the range is
10-2 or 8
46
what measures the standard (average) distance between a score and the mean.
standard deviation
47
what kind of significance does a large standard deviation have
none
48
what kind fo significance does a small standard deviation have
some sig
49
why does a large SD have a decreased significance
increase variability
decreased number of participants
decreased difference in means
50
if you want to increased significance what can you do
1. decreased variability but decreased SD and variance
2. increased the number of participants
3. increased the difference of means
51
what percent of of the scores will be within 1 +/- standard deviation of the mean for a normal distribution
70%
52
what percent of of the scores will be within 2 +/- standard deviation of the mean for a normal distribution
95%
53
what percent of of the scores will be within 3 +/- standard deviation of the mean for a normal distribution
99%
54
what does the z score tell you
exactly where the score is located relative to all the other score
55
if the z score is positive what does that mean ? negative ?
if it is postivie that mean X value is located about the mean and if it is negative then the X value is located below the mean
56
The numerical value of the ____ corresponds to the number of standard deviations between X and the mean of the distribution.
z score
57
a score that is located 2 standard deviations above the mean will have a z score of what
+2.00
58
what z score always indictes a location above the mean by 2 standard deviations
z score for +2.00
59
when you change the population score to the population of z scores on the graph does the graph change
no
60
what is the formula for computing the z score for any value of x
z= X (your score) - the mean / standard deviation
61
You scored a 82 on a test with a mean score of 70 and a standard deviation of 12. Your z-score will be
1+ bc the standard deviation is 12 and the mean is 70 and you scored a 82 which is 12 above 70 which is the SD so u go up 1 SD from the mean
62
You scored a 70 on a test with a mean score of 70. Your z-score is
0
63
The fact that z-scores identify exact locations within a distribution means that z-scores can be used as what 2 statistics
descriptive statistics and as inferential statistics.
64
what statistics does the , z-scores describe exactly where each individual is located.
descriptive
65
what statisitcs does the z-scores determine whether a specific sample is representative of its population, or is extreme and unrepresentative
inferential
66
what is the advantage of standardizing distributions
that 2 or more different distributions can be compared
67
N=60, Mean=83, Standard Deviation=10, what is the Z-score for 83?
0
68
N=32, Mean=120, Standard Deviation=23, what is the Z-score for 143?
+1
69
• N=1000, Mean=100, Standard Deviation=8, what is the Z-score for 92?
-1
70
N=50, Mean=50, Standard Deviation=10, what value has a Z-Score of -2
30
71
what are methods for using sample data to make general conclusions (inferences) about populations.
inferential statistics
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for inferential statistics what does the research begin with and what does the actual research do
begins with a question about a population and the actual research is conducted using a sample
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Rather than just describing the sample data (descriptive statistics)...inferential statistics use the sample to do what
infer something about the population in terms of probability
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When a set of scores is represented by a frequency distribution and that distribution is similar to a normal distribution, probabilities can be defined by
proportions of the distributions
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Probability =
Proportion
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When graphed, probability can be defined as what
the proportional area under the curve.
77
Drawing a vertical line through a normal distribution divides the distribution into two sections what is the larger section called and what is the smaller sections called
larger section is called the body and the smaller section is called the tail
78
what will give you ALL POSSIBLE proportions/probability for every z score.
the unit normal table
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so if you know the z score what can u look up ?
proportion/ probability
80
if you know the proportion/probability what can you look up
z score
81
if the z score is 1.96 how much of the area is in the tail
2.5%
82
If we think if the area in the tails when we use 1.96 (to the right)...and -1.96 (to the left)...there would be a total of ___ % in the 2 tails.
5
83
Do we use the normal distribution when running statistical tests
no
84
what theory is as the sample size increases it approaches a normal distribution.
central limit theorem
85
the smaller the sample size the smaller the ___ will be on the graph
tail
86
Population data can be ANY size and shape....but thanks to the central limit theorem…
single sample of 30+ it will be very close to a normal distribution
87
N>30 is only ___ assumption for parametric testing
1
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A sample size of ___ is often used as a rule of thumb for statistics since the sample of scores will be approximately normal.
30
89
what software do we use for a better estimate of the number or participants needed for a study
g power
90
If we are comparing more than two groups or time periods, or we have a factorial research design (2+IV) we run a statistical test called and what distribution does it use
ANOVA and it uses the F distribution
91
if we are comparing 2 groups or two time period we run which test ad what distribution does it use
t test and uses t distribution
92
if we are comparing the portions of people in different groups we use which distribution
the chi square
93
what test compares observed frequencies to what would be considered the expected frequencies
chi square
94
what is a value that describes the difference between the sample mean and the true population
standard error of the mean
95
what measure the amount of variability or dispersion for a set of data from the mean ?
SD
96
what measures how far the sample mean of the data is kiley’s to be from the true population mean
standard error of the mean
97
is the standee error of the mean smaller or larger then the SD
always smaller
98
a small standard error of the meal is interpreted as what
less sampling error
99
as the sample size increased what happens to the standard error of mean if the SD stays the same
it decreased
100
what is the equation for standard error of the mean
SD / square root of N (sample size)
101
most researchers will report what estimation
point estimation and interval
102
what estimation is a mean of your sample
point
103
what estimation is a span of number values that incorpates the mean
interval mean
104
what estimation is the sample mean...and it is used to estimate the population me
point
105
My sample of entering DPT students has an undergraduate GPA of 3.4 (95%CI: 3.2-3.6), so I will assume that the population of all DPT students has a GPA of 3.4.. what foes the CI mean
I am 95% confident that the real population mean is between 3.2 and 3.6.
106
what is a range of numbers inferred from the sample that has a known probability of capturing the true population parameter over the long run (ex/ over repeated sampling).
interval estimate AKA a confidence interval
107
The "beauty" of adding confidence intervals to your results is that the reader knows the probability that what
the true mean has been reported
108
Functional Outcomes in those with CVA and TBI after residential inpatient care at NeuroRestorative in Houston
Is this a prospective study?
Is this a 1b level study?
Is this a truly experimental study?
Could this study be reviewed using a PEDro scale?
yes and the. no 3x
109
If the calculated t-score is greater than our calculated t-value...it’s ____ . (2-tail)
significant
110
which sample mean is more likely to closer to the population mean?
which ever sample mean is closer to the actual mean
111
in box plots what does the box show
the median
the upper and lower quartile (25% and 75%)
the limits within which t middle 50% of scores lie
112
in box plots what does the box show
the median
the upper and lower quartile (25% and 75%)
the limits within which t middle 50% of scores lie
113
in a box plot what does the whiskers show u
the range of scores
th eli it’s within which the top and bottom 25% of the scores lie
114
in the error bar charts the bar usually showwhat score
the mean
115
in the error bar charts the bar usually showwhat score
the mean
116
The error bar displays the precision of the mean in one of three ways:
› The confidence interval (usually 95%)
› The standard deviation
› The standard error of the mean (SEM)
117
no
